# Crazy (Christmas) Project - Belt Sander



## wobblycogs (19 Nov 2010)

I don't want to waste anyones time so I'll state up front this project is probably crazy but I fancy giving it a go and if nothing else I'm sure it'll provide some amusement.

A while back, like many people here, I watched / read about this project to make a wooden bandsaw http://woodgears.ca/bandsaw/build.html and ever since seeing it I've fancied making one of my own. I could probably afford to buy a bandsaw but I'm fascinated by the idea of making my own machines if I can.

Anyway, I'm still comparatively new to woodwork so I've been trying to think of something that I could make that would use similar principals but be less likely to take my head off if it went wrong. The idea I've come up with is to make a belt sander a bit like this http://www.axminster.co.uk/axminster-axminster-awebds46-mkii-belt-and-disc-sander-prod725061/. This idea was finally cemented when I visited our local B&Q the other day and found a load of belts for £1.

So, my first question: do you think, broadly speaking, it's possible? Assuming it is what do you this tricky bits will be?

I plan on doing a full sketch-up plan but there are some bits that I currently know nothing about. One such area where I lack knowledge is with the axles, do I need bearings or would a friction bearing be sufficient? Due to how long the axles are likely to be rotating on a good sanding session I'm guessing bearings are a necessity but what type and where from? I'm also clue less when it comes to power transfer. I'm guessing a belt drive is the best option? I've Bobs workshop motor document a while back, think I'll go and have another read.

Ok, I've waffled on for long enough. I've got a load of time off over Christmas and my plan is to get this project completed by New Year if possible. I will, of course, do a WIP thread for everyone to point and laugh at  

Thanks for any help.

P.S. Hopefully by posting my intention here it will also shame me into actually making something...


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## Dibs-h (19 Nov 2010)

wobblycogs":21un63q1 said:


> Ok, I've waffled on for long enough. I've got a load of time off over Christmas




Don't mix it with the vino!! :wink: :lol:


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## Titus A Duxass (20 Nov 2010)

I have a Shop Notes article describing how to build a Belt Sander (also one for a disc sander and one for a mini lathe).

They are fairly straightforward but need a reasonable level of skill and access to some engineering parts (bearings & axle).

I going for a disc sander as my first project as it is a simpler build.

I'll get you some details of the bearings and axles if you wish.

I won't be doing a Sketch-Up of the project as Sketch-Up doesn't play with Linux.


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## monkeybiter (20 Nov 2010)

You will definitely need bearings, ball will be fine. I think the 'table' under the belt will need to be a polished metal plate, wood would heat and burn from friction.
Sounds like a fun project


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## wobblycogs (20 Nov 2010)

Thanks guys. I started doing some proper research last night and came to the conclusion that four 20mm pillow bearings with the axles sticking out to one side for the belt is the way forward (if the makes sense). I'm interested to see what your plans recommend though Titus both in terms of design and bearings. 

I also had a look for motors on ebay. I had assumed that the motor would be so expensive it would be cheaper to buy a sander but I was pleasantly surprised at how cheap a second hand motor is. I was thinking of going for about 500W.

From an engineering point of view the thing giving me most concern is tracking and tensioning. From what I can see looking at plans for real belt sanders they don't have crowned wheels so the belt must stay on purely because of the tracking (perhaps the crowning is very slight and I can't see it). I think technically this will be the most difficult part of the project.

Thanks for the advise on the table. I couldn't decide whether to try wood or go straight to metal so I think I'll just go metal on that part.


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## Titus A Duxass (20 Nov 2010)

I have seen some plans where the drive is through bicycle sprockets and chain.
The plans that I have use 19mm BB ply all round, no metal work other than the axles.


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## CroppyBoy1798 (20 Nov 2010)

wobblycogs":23tlhrm0 said:


> Thanks guys. I started doing some proper research last night and came to the conclusion that four 20mm pillow bearings with the axles sticking out to one side for the belt is the way forward (if the makes sense). I'm interested to see what your plans recommend though Titus both in terms of design and bearings.
> 
> I also had a look for motors on ebay. I had assumed that the motor would be so expensive it would be cheaper to buy a sander but I was pleasantly surprised at how cheap a second hand motor is. I was thinking of going for about 500W.
> 
> ...



I'm hoping to make a drum sander soon, theres a thread in this form about it somewhere from a few months back. Anyway, I have a lenght of 20mm axle and two 20mm pillow block, the only problem being that I cant seem to find a 4" pulley with a 20mm bore, I think 20mm was hard to come by in general, they were all 19, 21, etc. Just something to keep in mind as you'll be using pulley and belt. Gonna hve to have the end of the shaft turned down to 19mm.


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## wobblycogs (20 Nov 2010)

Many thanks for that info CB. As per the wooden bandsaw I was planning on making the larger pulley out of wood so I should only need to find a metal pulley for the motor end assuming the motor doesn't come with one. I haven't yet come up with a way to fix the wooden pulley to the metal shaft though...

I have a variable speed woodworking lathe and I think if I drop the speed right down I could probably just about turn aluminium so if push comes to shove I could probably reduce the size of the shaft at one end.

Good luck with the drum sander. I found the thread for that last night while looking to see if anyone else had made a belt sander. Looks like a complex build.


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## SammyQ (20 Nov 2010)

Wobbley? British Blades Forum; search "Aly" and his range of grinders. They're simple, tested and easy to emulate. PM me if you can't find him; I've got a set of downloaded pikkies and details somewhere in the 'tuit' files...

Sam


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## wobblycogs (20 Nov 2010)

Wow, those grinders Aly makes are top notch pieces of kit. I don't think I'll be able to emulate that build quality for this project as I have no metal working kit. While I would love to get a welder I think that's a step too far for now. Some good ideas there though, cheers.


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## SammyQ (20 Nov 2010)

Cheers. Just remember, you don't need a welder to build a look-a-like. Tapped holes and nuts/bolts will suffice, given you are not putting massive tension on the belt. Also, look at the VERTICAL sanders, not the big wheel HORIZONTAL ones. The square bearing plates are cheap as chips on the web and the basic frame is quite simple. (Ses he, who knows all this and hasn't bothered his rear end doing anything about it...).

Sam


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## CroppyBoy1798 (20 Nov 2010)

wobblycogs":2z3rwx3d said:


> Wow, those grinders Aly makes are top notch pieces of kit. I don't think I'll be able to emulate that build quality for this project as I have no metal working kit. While I would love to get a welder I think that's a step too far for now. Some good ideas there though, cheers.



While most of the bits and bob I've got out of Aldi over the years has been rubbish, one of the best buys was the arc welders that they sell from time to time. Well worth picking up if you see them come up again. The rods they sell are rubbish, but the welder is fine and has done a heck of a lot of work for me, from making gate/door frames to heavy shelving and brackets.


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## kirkpoore1 (20 Nov 2010)

wobblycogs":14zf3wif said:


> From an engineering point of view the thing giving me most concern is tracking and tensioning. From what I can see looking at plans for real belt sanders they don't have crowned wheels so the belt must stay on purely because of the tracking (perhaps the crowning is very slight and I can't see it). I think technically this will be the most difficult part of the project.



The drums on belt sanders are crowned. It is slight, so you have to put a straight edge on one to see the crown, but it's definitely there. You will still need to adjust the tracking, however. I can try to dig up the pictures of my Powermatic belt/disk sander restoration to give you an idea of the mechanism, if you want.

For the platen, I would have originally said metal, but now I think you can get aways with hard wood or even thick MDF. Whatever you use, get some graphite fabric to glue down on it. It cuts down on the friction and when it shows real signs of wear, you can take it off and replace it. That way your platen will not get worn out.

Kirk


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## wobblycogs (20 Nov 2010)

Pictures of the tracking and tensioning system would be interesting but don't worry if you can't find them straight away. I've grabbed a copy of one of the Jet belt sanders manuals which has a pretty good diagram. My plan currently is to mount the free running wheel in such a way that it can be tensioned and adjusted by turning two or three bolts. 

Never heard of carbon cloth before, I'll have a look for some tonight. Starting to put together a shopping list now. Found some cheap bearings earlier - they'll probably break down in no time but I think I'm going to have to treat this project as a learning exercise...


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## kirkpoore1 (20 Nov 2010)

wobblycogs":smy8n7se said:


> Never heard of carbon cloth before, I'll have a look for some tonight. Starting to put together a shopping list now. Found some cheap bearings earlier - they'll probably break down in no time but I think I'm going to have to treat this project as a learning exercise...



This is the sort of stuff you're looking for:
http://www.abrasivesupply.com/Stroke_Sander_Graphite_Cloth_s/288.htm

Note that the price is by the yard, but of course that will give you enough for several sanders.

Kirk


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## xy mosian (20 Nov 2010)

wobblycogs":j1zjt6oi said:


> .... I'll state up front this project is probably crazy ....


Yeah you're probably right . So what, you'll learn a hell of a lot and enjoy yourself, well some of the time anyway. All power to your elbow.

Some years ago I designed and built a powered fretsaw/ scrollsaw. I'm now on version 3 or 4. Now it doesn't get used a lot, which is why I built rather than bought. Yesterday, in use, the top blade holder came loose on the blade, first time, and as there was no method to constrain it, it shot up to the ceiling in the loft bounced off the kingspan and departed to another galaxy. So do I spend twenty years looking for it? It's about 16mm diameter and 18mm long. Or do I make another, if so now where are all my taps etc. Still, Hey Ho.  

Belt tensioning and tracking. Off the top of my head how about tensioning each bearing of the trailing roller separately? That way you can use the same arrangement for the tracking.

HTH
xy


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## wobblycogs (25 Nov 2010)

Right then, some frantic research later I've started the design but I seem to have run into a dead end so I'm hoping to get some suggestions . Note that it's far from complete (loads of supports etc missing) but I wanted to get the difficult bit, tensioning and tracking, nailed first. So, here's what I've got so far:

Front






Back





Everything was going fine until I went to insert the platen and realized that I didn't have space for it hence the over lap on the right hand red bolt. The carriage that carries the idler wheel is held down by the blue bolt which runs in a slot on the base plate, a wing nut on the under side locks the idler carriage in place once it's running true. The two red bolts are used to adjust the tension and tracking while the blue is slightly loose. Do you think this will work? 

I'm a bit concerned that if I move the right hand red bolt over it will have too course an action to set the tracking correctly. Two bolts for tracking and tensioning also feels like it will be overly complicated to adjust. Presumably I could replace one of the red bolts (the right hand one I think) with a spring but that feels like I'd be complicating the design even further.

On to motors now. I've never bought a motor before but I've finished Bobs guide and a few other resources and I'm thinking a .55kW 4 pole foot mounted singe phase motor is the way to go. I currently have 10cm belt wheels (are these called pulleys too?) on the design which my calculations indicate will give about 450m/min at 1400 rpm. Sound about right? Can anyone recommend a good motor that fits this spec or would I just be better going for a cheap one from eBay?

And there was me thinking this was going to be an easy first project...


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## xy mosian (25 Nov 2010)

How about moving the right hand, fouling, bolt to be in line with your clamping nut and bolt. This for the tension. Then make the left hand bolt captive in the slide so that its movement 'rocks' against the clamping bolt for the tracking?
HTH
xy


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## wobblycogs (26 Nov 2010)

Thanks for the idea XY but I decided to bite the bullet and go with a sprung design as seen below. I'm pretty happy with this design now. It looks simple enough to build and should be adjustable enough - I realized that commercial designs have the tracking bolt right next to the wheel so mine should probably be more accurate.






There's a problem though, I've priced up the parts and it's only worth building if I'm doing it for fun / learning. Once I've added in all the bearings, pulleys, bushes, motor, nvr switch and countless other little bits and bobs the price comes to about £200 which is the same as a really nice belt sander from Axminster. The only way I can really justify the build is if I can buy parts that will be useful on other projects so...

Bearing in mind that I want to build a bandsaw (that cuts wood and metal) and a CNC machine at some point I'm going to need an inverter. Searching on ebay I found item number 230493817712 (just stick the item number in the search field), a 2.2kW inverter from Hong Kong - Part No Huanyang HY02D223B. Reading 9fingers induction motor document this is, I believe, what I need to run a three phase motor with variable speed. The added advantage of an inverter, of course, is that three phase motors seem to be a lot cheaper and more reliable.

So my (dumb) questions are: 

0) Does this inverter convert single phase 230V to three phase (230V)? Pretty sure that's what it does but I just want to check 
1) This inverter is 2.2kW (output presumably) can I power a much smaller motor with it? I would like a 0.55kW motor on the belt sander but (probably) a 2.2kW motor on the bandsaw and about 1.5kW on the CNC machine.
2) Can I fit a standard three phase industrial socket to the output so that I can easily switch the inverter from one machine to another?
3) How easy do you think it will be to switch from one machine to another, will it require a lot of re-programming? I read a thread on a CNC forum where people were talking about manual programming that was needed to run the router motor - these are very high RPM motors though so perhaps they are outside the standard settings.

I've got a manual for this range of inverters which I can supply if it helps. Many thanks again folks.


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## 9fingers (26 Nov 2010)

wobblycogs":1ubjyxq7 said:


> So my (dumb) questions are:
> 
> 0) Does this inverter convert single phase 230V to three phase (230V)? Pretty sure that's what it does but I just want to check
> 1) This inverter is 2.2kW (output presumably) can I power a much smaller motor with it? I would like a 0.55kW motor on the belt sander but (probably) a 2.2kW motor on the bandsaw and about 1.5kW on the CNC machine.
> ...



I saw the beginning of this thread and considered the OP to even more eccentric than me and did not read on. In response to a PM I now see that the op is still digging. I have to admire the enthusiasm but still doubt the sanity :lol: 

My thoughts on the questions:-

0) Yes - therefore the motors you buy MUST be dual voltage 230/400 types with 6 terminals and need to be wired in delta (230 volt) mode

1) The inverter should be able to be programmed to say 125% of the current ratings on the motor plate. This will need to be changed every time you swap motors. Motor inverters will measure the stator resistance each time it is switched on.

2) Using a plug and socket connection is potentially risky as it could be possible to damage the inverter if the motor is unplugged without the inverter being switched off AND the motor being allowed to come to a halt. Also it would be easy by mistake to connect a low powered motor when the inverter remains programmed to a higher power setting. This means the motor is not adequately protected and could be damaged if there was a mechanical overload.

3) I think this is covered mainly above. In addition programming usually needs many key pushes and entering of motor specific data.

Yes it is possible to just use a single inverter but will need self discipline to avoid problems.

Although more expensive I would always advocate separate inverters matched, programmed and hardwired to each motor.

I do have one installation with a single inverter switched between two motors but these are equal power motors and the changeover switching can only be achieved when the power is switched off. It is almost impossible to get this wrong.


hth

Bob


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## wobblycogs (26 Nov 2010)

Many many thanks Bob. I'll bear that in mind when deciding whether to go ahead with this particular project. I actually have three phase power to the house it's just that because of the state of the place I can't get three phase to my current workshop (a first floor bedroom).

What I'm currently thinking is this: get a big inverter (3kW say) and a 0.55kW three phase motor for the belt sander project. When I move to my real workshop in the cellar I'll run in three phase power and use that directly on the belt sander freeing up the inverter for use on the bandsaw - if I understood your motor document correctly an inverter is needed for variable speed.

I think the inverter has a RS485 port which can be used to program it. I'm on much more familiar ground with programming, I wonder if I could knock something together that allowed me to switch programs at the touch of a button... project for another day I think. I hear what you are saying regarding the plug and socket though, will have a think about whether it's worth the risk.

What I lack in skill I try to make up with enthusiasm and lots of reading. I should have become an engineer rather than a programmer - it's far more exciting building things in the real world.


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## 9fingers (26 Nov 2010)

wobblycogs":39uxbqut said:


> Many many thanks Bob. I'll bear that in mind when deciding whether to go ahead with this particular project. I actually have three phase power to the house it's just that because of the state of the place I can't get three phase to my current workshop (a first floor bedroom).
> 
> What I'm currently thinking is this: get a big inverter (3kW say) and a 0.55kW three phase motor for the belt sander project. When I move to my real workshop in the cellar I'll run in three phase power and use that directly on the belt sander freeing up the inverter for use on the bandsaw - if I understood your motor document correctly an inverter is needed for variable speed.
> 
> ...




I wondered if you were a programmer when you numbered your questions starting with zero!!

You should be able to block download parameters via the 485 port. You already have a manual so you might be able to judge how easy that might be.

Most inverter manuals are written by people who are highly familiar with their particular inverter and often over look some critical item of info that they know and is obvious to them.
A bit like programmers writing software manuals! :lol: 

One possibly flaw in your future inverter plans. Inverters are either 240 in/240 out or 415in /415 out (although there are some now that are 240 in 415 out).
Currently you need a 240 in 240 out inverter for your sander, so when you run your three phase bandsaw from the inverter, it will have to be a dual voltage motor and the inverter will still have to be connected between one phase and neutral.
The ebay listing for the inverter is confusing where is says the input can be single or three phase.

hth

Bob


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## wobblycogs (26 Nov 2010)

Ok, I've just read your post three times and it's now clicked that the problem is. If I buy a dual voltage motor for the sander and the bandsaw I think I've got all angles covered. When the sander is on the inverter it will be in 230V configuration and when I move the sander to be directly powered off 3ph I can switch it to 415V configuration.

From what I've read I'm not convinced that the inverter can actually take 3 phase input. I suspect that is one of a multitude of mistakes in the listing. I'll have to dig through the 70 pages of badly formatted and translated manual to find out for sure. If it can I can't find anyone that has wired it up that way.

I've not been able to find a 230 --> 415 inverter and as you say they are probably quite expensive at the moment. All things considered I'd rather make everything that is going to have a 3ph motor run be able to run at 230V as it's highly unlikely I'll be living here forever and it was a fluke that we bought a place that had 3ph fitted (the house was bed sits and all heating and cooking was electric hence the need for loads of power). Who knows though maybe I'll fall in love with this house one day.


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## wobblycogs (4 Dec 2010)

Ok, so I bottled it and went with a 1HP single phase motor I found going fairly cheap and most of the other parts have arrived now too . The springs I received from ebay are the wrong type (tension rather than compression) and the guy's not responding so that could cause a hold up. I also haven't got a v-belt yet as I don't know the final distance between centres for the pulleys.

I do, however, have one quick question about motors. Is it possible to run them at any angle or do they have to be upright? The motor I have is foot mounted with box containing the capacitors on top. This makes the motor quite tall and it would improve the design if I could have the motor mounted on it's side.

A word of warning to anyone thinking of making one of these - don't bother unless you are doing it for fun as it would have been a *lot *cheaper and simpler to just buy one :lol:


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## Chems (4 Dec 2010)

If your going to all the trouble why not make a full sized wide belt sander


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## 9fingers (4 Dec 2010)

wobblycogs":23xmjnfj said:


> I do, however, have one quick question about motors. Is it possible to run them at any angle or do they have to be upright? The motor I have is foot mounted with box containing the capacitors on top. This makes the motor quite tall and it would improve the design if I could have the motor mounted on it's side.



You can run motor in any attitude. Make sure that you do not obscure any vents and if you have an older style motor with openings through to the windings, make sure debris cannot fall or get sucked into the windings & bearings.
Modern TEFC (totally enclosed fan cooled) motors look after this problem and are superior to open frame motors.

hth
Bob

EDIT: many TEFC motors allow the mounting feet to be bolted on in different positions which normally allow the capacitors to be either at the side or on top with respect to the feet. Somtimes the holes are ready tapped or other times they are cast in but need tapping typically M8


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## wobblycogs (4 Dec 2010)

Champion, thanks for that Bob. I hadn't noticed the feet could be moved as everything is painted a very dodgy orange colour. I've got a TEFC but I plan on taking extra care to make sure dust doesn't get near the motor anyway.


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## 9fingers (4 Dec 2010)

I'm not saying all TEFCs allow this but many do. look for cast in bosses in between the fins every 90 degrees round the casing

such as in figure 4 here http://homepage.ntlworld.com/bob.minchin/Induction motors - Issue2.pdf

Bob


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## wobblycogs (4 Dec 2010)

Sorry, I didn't make myself very clear. I've already checked out the motor and the feet can be moved. It's clearly been painted after the feet were bolted on because literally everything on the motor is orange: case, nuts, bolts, washers etc. Because of the paint job I missed the fact the feet were bolted on, I had assumed they were cast as part of the body. I'll need to get some taps though by the looks of it as I don't think the holes are threaded - cheap Chinese motor . Thanks again.


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## 9fingers (4 Dec 2010)

You 'might' find that the screws are self tapping that hold the feet on rather than buy taps??

Bob


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## wysong (11 Dec 2010)

As *Kirk *has pointed out the belt tracking is the hardest part to 
adjust , your tracking adjustments has to be available to you 
not hidden in the machine , the belt will never have a chance of staying on 
it take split second adjustments , depending on what your sanding
and where on the belt your working .

The first picture here is of the mechanism of the belt side for a
General 100 Sander (similar to Kirks PM 30 ) the belt size is 
6" by 60" , disk is 16" 







the second picture is the actual machine 
which is simlar to the Wadkin version 





you can see in the second picture , this is the tracking adjustment 
for the belt , a slight turn with the belt running sends it either way 
the outside of the roller is pined , and the adjustment is on the inside 
of that roller .

Hey Kirk , found ya over here too.


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## wobblycogs (11 Dec 2010)

Cheers, I've partially re-done the design and I'm about to start cutting out the pieces. the tracking knob is a little obscured but I can open it up a bit and if necessary I could probably alter the design to put it on the outside. The tracking adjustments shown in those two pictures are almost identical to the design in the only other home made (wooden) sander I've seen.


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## 9fingers (11 Dec 2010)

So the medication is not really working yet then? :lol: 

Bob


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## wobblycogs (11 Dec 2010)

Nope, in fact I think it's caused the problem to get worse. The prospect of maybe becoming unemployed in the new year is the only thing that will slow my machine building frenzy down I think. I'm currently trying to make enough space in the workshop to lay an 8x4 sheet of MDF down for the first cut. The workshop is, as always, a right bleedin' mess so I will probably only get that one cut done today.


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## 9fingers (11 Dec 2010)

wobblycogs":2rcrnbg4 said:


> The prospect of maybe becoming unemployed in the new year is the only thing that will slow my machine building frenzy down I think.



Lets hope the job keeps open for you! Good Luck

Bob


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## wobblycogs (12 Dec 2010)

Thanks for the support regarding the job. It's actually rather worse than perhaps I made it sound. I'm a one-third owner of the company and we've just found out that we will be losing two of our biggest clients as they are trying to cut costs. Not the worlds greatest Christmas present but we aren't quite down and out just yet, cross your fingers for me.

Anyway, on with the project. I've now cut all the pieces out of MR-MDF. I hate working with MDF, It seems no matter how much extraction I've got going the dust still seems to go everywhere. A problem not helped by the fact I did a lot of the cutting with a jigsaw and a SCMS which are impossible to collect dust from effectively (IMHO).

The first cut, I only include this because it shows off the track saw attachment I made a while back. It's proved to be surprisingly accurate and useful. I've decided that one day I have to save up for the real thing.





Next was marking out. I went for the straight edge and knife approach. I managed to arrange it so that all the parts fitted into a piece of MDF 1220x725. This doesn't include any tables or stops which I'll be making separately once I've proved that the machine generally works.





Finally after a couple of hours turning the workshop green we have all the parts cut





I'm not over the moon about my level of accuracy on a couple of the parts (unfortunately the larger ones) but the parts that I think really matter I ganged up and cut in one pass so I think I'll get away with it. The one thing that is concerning me is drilling the holes for the bearings. They have to be pretty much bang on perpendicular to the fact of the MDF but I don't have a pillar drill. I'm thinking I'll probably make up a jig and route them.


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## wobblycogs (25 Dec 2010)

Ok, sorry for the lack of updates to anyone following this build. I've been rather ill over Christmas but I've still managed to shuffle out to the 'shop now and then and make some progress. I decided to set up a new website to document my wood working exploits so you can find the intermediate steps with loads of photos here:

http://www.wobblycogs.co.uk/index.php/projects/belt-sander

I've got the sender to the point where I can run a belt around the two rollers as seen bellow:






I haven't fitted the tracking mechanism yet, that should go in tomorrow - it needed a bit of a rethink. The tensioning mechanism works well but I think I'll need a third spring. There is a little bit of vibration from the primary sanding wheel, I must have done a poor job of turning it! I think I'll probably sand it round in situ so it's perfectly balanced. The crowning on the wheels works really well but there is too much crown so I'll also remove some of that. Really though I just need to fit the platen and any other tables / fences I want and I'm good to go.

Quick question: when I first started it the motor ran slowly, probably half the speed it should have. After about 30 seconds of running it burst into life and ran at it's expected 1300 rpm. It's very cold in my shop and I think the slow running was because the belt was cold and stiff and causing a lot of additional load on the motor. Once it had been running for a few minutes the belt was slightly warm (25 deg maybe? - hard to tell but certainly not hot) and much more flexible and the motor always got up to full speed in <0.5seconds. Do belts get slightly warm when running? Does a cold stiff belt sound like the right diagnosis?

I've also got a little 30 second (2.5MB) video of it running if anyone is interested:

http://www.wobblycogs.co.uk/images/projects/belt-sander-first-run.m4v

Merry Christmas everyone.


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## tisdai (25 Dec 2010)

A biggg well done m8 =D> , that is looking spot on. I like the little vid of it working, 

Cheers for sharing

Dave


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## 9fingers (26 Dec 2010)

Very impressive Graham!
I suspect that you are correct in blaming the temperature for the slow start up although it could possibly be the wrong type of motor providing insufficient torque. However the fact that it does reach synchronous speed eventually does point to being either underpowered or belt/temperature issues.

A belt drive is not 100% efficient so yes this wasted power does come out as heat in the belt and the pulleys.

If the machine continues to be a slow starter when the weather is warmer then you do need to sort it out. 25 seconds for the starter winding to be powered up is too long and might eventually lead to the magic smoke escaping.

Good luck

Bob


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## wobblycogs (26 Dec 2010)

Thanks again Bob, looks like it's just that the belt was cold. After a freezing night in the shop I brought the machine into the living room for a hour or so to warm up and on first starting it got up to speed in <1second. I'm pretty confident that the motor is powerful enough at 750W (commercial machines using this belt size seem to be around 500 to 600W) and it's a cap start, cap run motor so it's got a decent starting torque. By god it's got heavy quickly though - it must weight about 25kg and there are still bits to add.


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## 9fingers (26 Dec 2010)

Ah! yes 750 w and CSR will be plenty as confirmed by your test. For future reference (for your next machine build), using flat, poly Vee or timing type belt are much more flexible than single vee type belts and to be preferred for small (sub 3" say pulley diameters).

Cheers

Bob


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## wobblycogs (26 Dec 2010)

Now you mention using poly-vee belts that makes perfect sense. My lathe has a poly-vee and I remember seeing them on pillar drills too. Good to know for next time.

I've literally just finished fitting the tracking mechanism and it works perfectly   . A little turn of the wing nut in either direction and the sanding belt shifts across the wheel. If I push the belt to one side with a scrap of wood it re-centres itself within a couple of revolutions.


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## Titus A Duxass (26 Dec 2010)

It's coming along nicely, I'm looking forward to the end result.


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## danhorn (16 Apr 2013)

Cool Project. I see you have a photo for the Belt Sander side from the manual for a *General 100-5 Belt Sander/16" Disc Sander*. 
I have the same model here at our school. I'm trying to get the shaft off out of the bearings so i can replace the belts. What a pain. #-o 

Any chance any one who sees this has a full copy of the manual I could beg borrow or steal? electronic format extremely welcome. 

I'm just not sure how to get the shaft off or what i seem to think is a pressure fit ring on the belt sander side of the shaft that will allow me to pull the shaft to the middle of the machine to remove the belts since they seem to be locked in between the bearings until "something" is removed to allow for replacement. 

Any one who reads this post : Much appreciated

Dan


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