SCM Minimax S45 Bandsaw Teardown & Overhaul

[Jitter]

Not a hugely productive day today. The new owner asked for a mains cable 5m long…….and as is typical we had just 4m left……not a big deal, we had anticipated supplying a cable of circa 3m, so hadn’t ordered a new real. Rather than relying on the unreliable post we popped to the local electrical distributor to pick up some additional cable. We selected a particular type of cable for this saw, Sideways will explain the rational as he is in charge of the rewiring of the machine. We always replace all the cables in a machine, with age they become brittle and for us it’s a false economy for the new owner if it isn’t rewired throughout.

My apologies Deema. I should have had the cable distance measured out well before now. In all honesty, I should have realised you needed the length size when you asked how I was needing to connect the machine to the transwave and did not expect you would be actually wiring it up ready to use. When I bought the Wadkin, it arrived without a cable or plug, I paid my sparky friend to wire it all up once the machine was in place, he supplied the parts after seeing it in place. 4 metres may well have been enough length to get me started, I added a metre because it may be in future that I will pull the machine away from the wall to maximise flexibility of use when cutting. You have obviously bought quite a bit now for the saw and for reasons that will benefit me greatly and really appreciate it. Please do let me know if I can help with the funds at all, I did expect to have to pay my sparky to wire it up after arrival so happy to help with the cost of at least that.

The S45 is looking great. You guys are making it look like new. If I ever meet another with an S45, I will be pointing them to this thread, it’s like Haynes manual step through guide with a personal touch and better pictures!

 

[TRITON]

I’m so sorry, you were pipped to the post by another member of this forum. It is detained to fly north when we have it finished.

Up North ?.
Well thats ideal. A nice bright colour will show up in the snow and mean it will never get lost

 

[deema]

Sideways and I have made a bit more progress, the wiring is all done and electrically tested, Sideways will I’m sure detail what was involved.
The table insert is made, and the new owner will also receive an brand new SCM official insert, which I believe are plastic. The one we have made is aluminium. I’m biased, but I like a metal insert.

The fence has been cleaned up and fitted, it’s perfectly square to the table which is great.

The belt that came off the saw, which I believe was original was an A37, which we replaced with like for like. However, an A37 was far too tight and didn’t facilitate any tightening. So, we have ordered and now replaced it with an A38. I’d be curious to know what belts are on other peoples S45.

 

[Jitter]

The insert plate looks perfect. Great to know the fence is accurate too.

 

[deema]

We have started to setup the saw, first off is the vertical alignment of the blade. Before doing any adjustment we ensure that none of the bkade guides are anywhere near the blade, otherwise they affect the blade alignment. The bottom wheel is held by 4 bolts that adjust its alignment, these are used to both set the blade vertically square with the table and also to track the blade to cut parallel to the fence.

The bolts at 12 and 6 O Clock adjust the vertical alignment. The top wheel is used to track the blade correctly on the wheels, so, by nodding the bottom wheel either up or down tips the blade either forward or backward. As an aside, o should say that the hub of the two wheels need to be coplaner, or as close as possible or the adjustment doesn’t work.

The bolts at 3 and 9 o’clock are used to track the blade to the fence. So, if the blade is cutting away from the fence you tilt the lower wheel to correct this. You unscrew say half a turn one of the bolts and tighten the other. Now, the shaft that these bolts act on is round, so, you have to slacken one of the other pair of bolts. I.e. adjusting the bolts at 3 and 9 needs the bolt at 12 slackening. If you don’t, the adjustment won’t move the shaft as expected. Equally if you move the shaft two far, it affects the setting of the other pair of bolts. I.e. adjusting the alignment to the fence can also affect the vertical alignment. It’s a bit fiddly, and can either take a while or you can be lucky.

So after a bit of messing about, this is the vertical adjustment dialled in.

 

[deema]

Alignment of the blade to the fence is next.

This piece of ply is cut with the fence, you can see how far out the alignment was to begin with. The lower wheel needed to be tilted away from the fence. To do this we slackened the bolt at 3 and tightened the bolt at 9 o’clock.

This isn’t complete, I thought we had 3 or 4 good blades that came with the saw…….but when we examined them we found that two are for foam cutting, we used one of these for the verification plate alignment, and the third which is a wood blade was badly damaged. So, a new blade is required before we can complete the setup…..darn! Tufsaws will be getting an order.

 

[Sideways]

Interesting about the belts. When you overhaul an old imperial machine and fit a modern motor made to IEC / metric standards, one or both pulleys may need changing and belts usually do because the new motor has different dimensions. It is quite tricky judging the correct belt length from measurements even when you understand how belts are sized.
In this case, the motor is already IEC and in good condition. No need to change. The starting point was to fit a new belt the same size as the one taken off. Even the most straightforward swap can be tricksy.
Here you can see the range of adjustment available in the (original and unchanged) motor mounts for tensioning the belt. There's about 1 inch vertical movement in the slots of the four bolts. So the belt needs to be pretty close. With the A38 belt, the mounts are about the middle of the slot, rather than being over tight at the downward limit of the holes with an A37.

The motor is held by the four 4 bolts through a flange. The bolts are loosened, and the motor dropped to fit the belt. The lower band wheel is removed for a belt change as the belt is too small to be stretched over the wheel while it's in position. Once the belt is sitting in the grooves of the motor pulley and lower wheel, the wheel is refitted to it's spindle and the motor lifted by a jacking bolt until the belt is comfortably tight. About 1/2" sideways movement when you push firmly but not hard on the belt midway between pulleys is about right.

 

[deema]

Finally for today from me, I’d really appreciate some help from anyone with a SCM bandsaw. We are concerned that the spring which creates the tension on the blade could have been over compressed at some stage in its working life. If it has it will be shorter than it should be having taken a permanent set. I would be extremely grateful if anyone with this bandsaw could measure the length of the tensioning spring.

To Measure it, if you could be so kind to simply unscrew the tensioning handle until it comes out. The spring and washer just lift out. What we would really like to know is how long it is, measured as accurately as possible. It simply screws back in, no fitting or fiddling around to out it back in.

A big thank you in advance.

The spring in the saw is
Outside diameter 20.5mm
Inside diameter 11.4mm
Wire diameter 4.6mm
No. Of coils 9.5
Length. 61.7mm. We think it should be possibly 6mm longer. This is the dimension we would appreciate verifying.

 

[Sideways]

Interesting about the foam cutting blade in Deema's photo above. It's scalloped like a bread knife and has no set at all. I'd not seen one of those before.

 

[deema]

The table has a stop, which can be adjusted to ensure that the table always returns to be perpendicular to the blade. We reset it correctly. It’s just a bolt, however the nut inside the saw isn’t captive and it’s quite difficult to reach to both slacken and then tighten. Again adjustments are done without the blade guides anywhere near the blade.

 

[Sideways]

The promised word on the wiring. The saw is all good now. 3 phase 16A red plug. HO7 rubber flex to a compact enclosure on the back of the saw where the contactor and overload relay are housed. Motor is wired "star" for a 380-400-415 Volt supply.
Start stop buttons and the safety switch for the doors all wired up and proven.

As well as functional tests, we do a couple of safety tests using an installation test meter. These devices include the ability to measure low resistances so the first tests ensure that we have a reliable connection from the ground pin of the plug to several points on the chassis of the machine. Zero the meter first to eliminate the resistance in the test leads, then a reading of 0 is what we want.

Motor housing

Table

Etc

The second set of safety tests makes sure the insulation of the wiring and motor are in good condition by applying a 1000V test Voltage and measuring any leakage resistance. The reading here is "Resistance greater than 1000M Ohms". This is what my tester says when it can't see any leakage so it's the right result and is repeated for all phases and with the contactor manually held in so that the motor windings are included in the test.

he other

 

[Ttrees]

Never heard anyone suggest the bottom wheel adjustment on flat tyres relates to tracking or "drift" !
surely that is done via the trunnion bolts.
Have heard it suggested before regarding crowned tires, but I'd take that with a pinch of salt also, as most folk don't seem very concerned about dressing tires.

In my book the bottom wheel setting is done without a table, as I also had that very same belt issue which I was to find out was an expensive lesson.
Misalignment of wheels + belt too small = damaged motor bearings when ran for only a second.

That said it all as far as I'm concerned, the top wheel rules over anything and hopefully the pulley will match.
Everything else is adjustable, even if it isn't .


Must check my belt now, to see what size it is, seems/pot shot guess they are made in inch increments from what you say.

I thought my spring looked compressed, but found a factory bit of footage showed the same.
Haven't seen much on these machines to suggest anything, and have went to the far corners of the interweb looking
At various machines and whatnot.

I could tell ya Eric Loza on the creek would be one fella I'd chance asking. (He doesn't work for MM no longer)

Tom

 

[deema]

@Ttrees, firstly an admission; Sideways checked the tyres yesterday and reported them to have a slight crown. So, my error, I’d believed that this saw had flat tyres.
The top wheel mechanism normally is designed to have a lot of slop, so you can without a blade move it wiggle it around a vertical axis. It will therefore follow the lower wheel. With a new sharp blade, properly set teeth and tensioned, you can adjust the tracking using the lower wheel adjuster bolts. There are lots of things that affect the drift of cut, from position of the blade in the wheel, how stress relieved the blade is, set of the teeth, tension etc etc. however, logically, if you look at the construction of a bandsaw, there are no reference machined surfaces for the wheel mounts, so, it has to have adjustment to get everything working together properly.

 

[FlatlandsF7a]

Sideways and I have made a bit more progress, the wiring is all done and electrically tested, Sideways will I’m sure detail what was involved.
The table insert is made, and the new owner will also receive an brand new SCM official insert, which I believe are plastic. The one we have made is aluminium. I’m biased, but I like a metal insert.
View attachment 128476

The fence has been cleaned up and fitted, it’s perfectly square to the table which is great.
View attachment 128477

The belt that came off the saw, which I believe was original was an A37, which we replaced with like for like. However, an A37 was far too tight and didn’t facilitate any tightening. So, we have ordered and now replaced it with an A38. I’d be curious to know what belts are on other peoples S45.

Just to note that the belt on my S45 is an A38, but it also looks newer than the saw, so I suspect it was replaced at some point in the life of the saw, probably with the exact same experience as you.

On the spring size, mine was compressed fully for a long time, and it came in at almost exactly 60mm long, but I don't have the number of coils to hand I'm afraid.

Thanks again for this whole thread @Sideways and @deema, it is already really useful, and will definitely be in the future if anything goes wrong with my S45.

Finally, my machine doesn't have the rack and pinion rise and fall for the blade guard, and the travel isn't square to the table or parallel to the blade. Is it possible to retro-fit something like is on your version, as it looks much easier to use, and would save altering the guides every time the cut of height is adjusted?

 

[deema]

@FlatlandsF7a thank you so much for the measurement, I think you have a different generation of saw to the one we are working on if it doesn’t have a rack. I wasn’t aware they did a variant without a rack. Do you have a picture / serial number of the machine and I will see if I have a parts list for it.

There are two reasons we think it’s taken a set, firstly the saw is rated for standard blades between 6 and 20mm, and the spring when not compressed at all is just a smidge above the line indicating correct tension in a 6mm blade. Secondly, I think the clear acrylic pot has crazed due to the adjuster handle having been screwed down so far it’s actually compressed the pot. A sign they couldn’t get the tension high enough. (Although some blade materials, ie M42 need a higher tension, so a saw that takes a 20mm standard blade may not be able to fully tension a 20mm tougher material blade.) We are going to make a spacer to stop this ever happening again and also replace the threaded bar on the adjuster to make it longer to a accommodate the spacer.


If anyone else with a S45 could also measure their spring that would be really brilliant. If all three are the same / similar, we know it’s good.

 

[Ttrees]

@Ttrees, firstly an admission; Sideways checked the tyres yesterday and reported them to have a slight crown. So, my error, I’d believed that this saw had flat tyres.
The top wheel mechanism normally is designed to have a lot of slop, so you can without a blade move it wiggle it around a vertical axis. It will therefore follow the lower wheel. With a new sharp blade, properly set teeth and tensioned, you can adjust the tracking using the lower wheel adjuster bolts. There are lots of things that affect the drift of cut, from position of the blade in the wheel, how stress relieved the blade is, set of the teeth, tension etc etc. however, logically, if you look at the construction of a bandsaw, there are no reference machined surfaces for the wheel mounts, so, it has to have adjustment to get everything working together properly.

I noticed this with a far eastern 20" machine, but my acm seems pretty rigid, when locked at the back.
(Bar a issue with the spacer) which is very subtle.
Someone before me attempted to skew the wheel to suit the post, but obviously that didn't work.

Not the first time I've heard of some Italian machines with differing profiled rubber.
I'll try finding that link mentioning differing profiles on various italian machines, i.e. True flat, slightly crowned, more pronounced crowned.

Not sure if that "drift" /call it what you want, thinking, would suggest to keep adjusting the bottom wheel of not.
I've learned my lesson about setup, and if I wanted that profile on my wheels, and things were going aray, I'd just dress the tires rather than risking my motor bearings, and duffing the set on my blades.

That's my 2cents on the matter.
Might not be as apparent with a wheel which has a smaller hub, in which the belt rides, compared to my machine which it's quite large hub compared to most.

Can edit my post to add link about tires.
https://sawmillcreek.org/showthread.php?270375-A-Question-for-Flat-Tired-Bandsaw-Owners/page2All the best

Tom

 

[deema]

@Ttrees, I understand the concern and agree. The amount of movement you need to make in the wheel is very very small. The motor, wheel and table are when fitted initially all ‘aligned’ the tweaks are only very small and don’t affect the belt alignment. We check it and if it’s out too much would just shim the motor mounts. Probably the most important thing is not to over tighten the belt.
Belts come in 1/2” increments. I bought at A37.5 as well as an A38.

 

[deema]

@Ttress, thanks for the link to the other site, a very interesting read. The S45 manual states that the blades should be run with the teeth off the front edge……which is normal for a flat tyred machine. Sideways observation, and also a comment on the link is that they have ‘slightly’ crowned wheels. I can see a logic for this. I like flat wheel, I think they provide better tracking as the blade in not ‘balanced’ on top of the crown which can create variances in tracking. Flat wheels seem to track far more consistently, and are normally found on high end saws / saws of larger capacity. However, the S45 can take a 6mm blade, and tracking that width to run with the teeth overhanging the edge of the wheel would be a challenge. Folk on the link have said they would run small blades on flat tyres in the middle. So it seems that by having a slight crown you have the best of both worlds. Running the smaller blades in the middle of the wheel with a slight crown will leave space for the set teeth to sit without chewing up the wheel. Larger blades can run with the teeth overhanging the edge of the wheel.


I wish I knew how to thank threads rather than just add a like?

 

[deema]

SCM have been very kind to provide me with the dimensions of the spring. I don’t know what standard tolerances springs are made to, but ours is a little shorter (3.3mm or circa 5%) than the drawing. There is no bump stop in the design, so the spring can be compressed by the mechanism until the coils touch each other. So, either this is a poor design, or springs of this type can be completely compressed, I don’t know, are there any experts in springs?
We are having a bit of a think about the tensioner design, we already have one feature we are going to improve over the original design, but also wondering about other improvements. A replacement spring from SCM is part number 0332661250E and costs £38 plus vat. (Minimum order value £70 excluding VAT.)

 

[FlatlandsF7a]

SCM have been very kind to provide me with the dimensions of the spring. I don’t know what standard tolerances springs are made to, but ours is a little shorter (3.3mm or circa 5%) than the drawing. There is no bump stop in the design, so the spring can be compressed by the mechanism until the coils touch each other. So, either this is a poor design, or springs of this type can be completely compressed, I don’t know, are there any experts in springs?
We are having a bit of a think about the tensioner design, we already have one feature we are going to improve over the original design, but also wondering about other improvements. A replacement spring from SCM is part number 0332661250E and costs £38 plus vat. (Minimum order value £70 excluding VAT.)
View attachment 128522

I happen to have recently replaced my spring due to fears over it being over-compressed in the past (I made a thread on this site somewhere).

I ended up purchasing mine from Berger Tools which had a huge range and really good prices. I ended up buying 3, unsure of which would work best, and to reach the minimum order, and it all came to c.£15 including delivery. So excellent value.

I ordered the following:

G25-064	G Yellow Die Spring ISO10243, Extra Heavy Load	1	£2.51
G25-051	G Yellow Die Spring ISO10243, Extra Heavy Load	1	£2.30
G32-064	G Yellow Die Spring ISO10243, Extra Heavy Load	1	£3.34

But found that the G25-064 was the best replacement and the G32 didn't actually fit through the aperture in the saw case (I didn't think to measure that!).

Very interested on opinions on how (in)appropriate these might be. The G25-064 seems to be tensioning everything well, certainly better than the original that came with the saw.