CNC advice please

[bilboburgler]

Those ideas certainly chime with my thoughts. A drawing would be wonderful, thank you.

 

[Jester129]

Have to say this is a fascinating thread, cudos to you all. Will this drawing be available on the thread, hope so!

 

[worn thumbs]

The idea of pre-tensioning the ballscrews to prevent whip is entirely sound and might be a good deal easier if the machine was designed to operate with fixed ballscrews and rotating ballnuts.If one of the users of the makerspace has the ability to 3D print toothed wheels it might be that they would last a good while and then when a 4th axis has been introduced,more durable replacements could be produced.The ability to make the parts to replace itself has always been an appealing aspect of a machine.The disadvantage of having to include power cables for the steppers in the drag chains to the gantry is a modest one,although one or other will already be holding the power cables to the Z axis.

 

[Trainee neophyte]

I've just come across the following, and thought it might be of interest:

$500 allegedly...

 

[sploo]

The Maslow is an interesting concept. I looked at it some years ago as it's quite space efficient. That said, I don't think the accuracy is close to a "proper" CNC machine; so it's best suited for large sign cutting type work.

 

[bilboburgler]

One of our Maker Space members made one of those and the bits are still in the cellar. He likes the technology, but....

 

[worn thumbs]

The Maslow is an interesting concept. I looked at it some years ago as it's quite space efficient. That said, I don't think the accuracy is close to a "proper" CNC machine; so it's best suited for large sign cutting type work.

There endeth the good points.... I can't imagine what happens with a plunge cut.For similar space utilisation,there is no particular reason why you couldn't tip a conventional type of machine on it's side.

 

[sploo]

One of our Maker Space members made one of those and the bits are still in the cellar. He likes the technology, but....

It's definitely one of those "brilliantly original idea, but does it actually work (well)?" kind of things isn't it.

 

[Ollie78]

The idea of pre-tensioning the ballscrews to prevent whip is entirely sound and might be a good deal easier if the machine was designed to operate with fixed ballscrews and rotating ballnuts.If one of the users of the makerspace has the ability to 3D print toothed wheels it might be that they would last a good while and then when a 4th axis has been introduced,more durable replacements could be produced.The ability to make the parts to replace itself has always been an appealing aspect of a machine.The disadvantage of having to include power cables for the steppers in the drag chains to the gantry is a modest one,although one or other will already be holding the power cables to the Z axis.

I think ballscrew whip is unlikely to be an issue under most use cases, unless very long or very skinny. I remember reading some info about this ages ago.
I did see a very interesting solution to it where about the centre of the length they put a plastic thing that held the centre true, it was a fairly simple fork shape that cradled the screw, the clever bit was that it popped out of the way when the ballnut passed by and sprung straight back to position.
I think just going up a size of screw is probably easier though.

Ollie

 

[bilboburgler]

I think ballscrew whip is unlikely to be an issue under most use cases, unless very long or very skinny. I remember reading some info about this ages ago.
I did see a very interesting solution to it where about the centre of the length they put a plastic thing that held the centre true, it was a fairly simple fork shape that cradled the screw, the clever bit was that it popped out of the way when the ballnut passed by and sprung straight back to position.
I think just going up a size of screw is probably easier though.

Ollie

I don't think pre-tension is really there to solve whirl, I think it is to solve Euler collapse or at least Euler bending when the compressed part of the longest part of the screw moves out of line. Tension stops that screw getting into Euler bending and, of course, as a secondary result, stops any whirl that is due to that.

Going up a size on ballscrews means you also go up a size on bearings, nuts, and £ while equally puttting load on your axis motor. My present view is stick with 12 until you have a reason to go to 16 diameter.

I think I read higher up that pre-tension is difficult. I must be missing something because, if you have your ballscrew mounted in bearings on the end plates on either end of the aluminium extrusion then with one end held by a circlip and the other by a tighten-able nut then you have tension right there. It does of course question is the circlip a good idea and make sure you've done the termal calculation for steel/aluminium at say 20C and say 0C for a workshop without heating.

I'm thinking of proposing to build just a Z axis as a demonstrator for the Space, it should let us see the beast, play with the axis motors and slide plus the software at a low cost. Plus it allows me to design something as light as possible with standard components. If no one shows any interest it allows me to focus on alternative projects for the Space.

 

[Phill05]

I'm thinking of proposing to build just a Z axis as a demonstrator for the Space, it should let us see the beast, play with the axis motors and slide plus the software at a low cost. Plus it allows me to design something as light as possible with standard components. If no one shows any interest it allows me to focus on alternative projects for the Space.

I don't think you need to think about pretension, I also think for the size of machine you said, I would go for 16mm ball screws and 20mm rails and then no matter what you want to cut it will be man enough to tackle it.
12 mm ballscrews do not have much depth to hold the balls.

Here is an image of the extended Z axis when I was in the process of making it, I wanted to put a 4th axis on the bed to turn a 330 mm high stone disk and cut a relief shape around the circumference.
I have also cut gear teeth around a 280 mm clock wheel.
This is made with 20 mm linear rails 16 mm ballscrew and the ball nut is rotating at the top powered by a Nema 23 motor, I wanted to to get the least amount of overhang so no traveling ballnut.
The Z axis is pivoted so able to swing left or right around 20 deg it is also demount-able and able to be moved to the Stone cutting cnc then put back on the metal/wood cutting cnc.
2nd image showing when I was fitting it up on the metal cnc.
3rd image show some work cut into wood.

 

[curryjunkie]

I only managed to read some of the posts, not the enire thread and, being in a similar situation with 'everything needs to come through the front door', I will share my journey. The CNC machine was on my bucket list and, after a lot of research, I chose the 1010 Workbee to be my machine of choice. At that time there were 3 popular versions: Ooznest for the UK market, Openbuilds for the American market and Bulkman 3D for the Asian market but all 3 selling everywhere. It was a hard choice. I mainly chose Openbuilds because of the proved and tested American quality. The UK was great, even improved, but the price difference from USD to GBP was pretty prohibitive for me. Bulkman's was cheaper but I was hesitant to make such a purchase from them. This was also 2019 and since then Bulkman built a name for themselves.

Out of nowwhere, in 2020 a Workbee dealer appeared in the Romanian market. I contacted them, stated my interest in buying the CNC and got no reply for a long time. Eventually I managed to find out that they didn't have the actual machines, they were distributing the CNC routers sold by a company from Portugal, by the name of RatRig. I also found out that RatRig were innovators experienced in 3D printing technology, a group of passionate people who added CNC machines to their portfolio. Not only added it but, after consulting with the community, added their own improvements.

After researching into it, I ordered their version of the 1010 WorkBee CNC. Soon after my purcahse, they launched their own design of a much improved version of the WorkBee, this time with linear raild and steel plates, called the KillerBee. I was annoyed for not knowing about it but it was my fault since I wasn't following their community at that time. After much consideration and saving the money required, I purchased the upgrade kit for my machine. Soon after my purchase and now owning a superb machine, they launched their Stronghold Pro CNC which is 100% their design, concept, integrating feedback from the community as well. It was again my fault because now, even if I was following their community, I had not paid attention to their updates...

This Stronghold Pro machine might be a good candidate for your needs in relation to the stated conditions. Might be worth checking it out. This is the link to their machines Routers - CNC Machines and here is the version I was referring to Rat Rig StrongHold PRO CNC - Standard Kit

They have a great customer support. And they also offer very solid tables and other accessories for the machines. Further, they have a helpful community where you can find all info you need before making a purchase decision.

Merry Christmas and happy holidays!


Brad

that kit looks pretty good value for money.

 

[Ollie78]

I don't think you need to think about pretension, I also think for the size of machine you said, I would go for 16mm ball screws and 20mm rails and then no matter what you want to cut it will be man enough to tackle it.
12 mm ballscrews do not have much depth to hold the balls.

Here is an image of the extended Z axis when I was in the process of making it, I wanted to put a 4th axis on the bed to turn a 330 mm high stone disk and cut a relief shape around the circumference.
I have also cut gear teeth around a 280 mm clock wheel.
This is made with 20 mm linear rails 16 mm ballscrew and the ball nut is rotating at the top powered by a Nema 23 motor, I wanted to to get the least amount of overhang so no traveling ballnut.
The Z axis is pivoted so able to swing left or right around 20 deg it is also demount-able and able to be moved to the Stone cutting cnc then put back on the metal/wood cutting cnc.
2nd image showing when I was fitting it up on the metal cnc.
3rd image show some work cut into wood.

View attachment 172877

View attachment 172878

View attachment 172879

Thats nice rotary work, any tips on the programming for 4th axis. Do you use Vcarve pro? I had a look at it and it seems you have to do a flat pattern and wrap it somehow. But, if I start with square stock do I need to rough it into round first.

Ollie

 

[Phill05]

Thats nice rotary work, any tips on the programming for 4th axis. Do you use Vcarve pro? I had a look at it and it seems you have to do a flat pattern and wrap it somehow. But, if I start with square stock do I need to rough it into round first.

Ollie

Yes you need to cut square to round on the 4th axis keeps it all true, to do something like the round bases you would start off making the 2 1/2D model you want to build with in my case i had made the shell for a set of drawers, I work in Vectric Aspire I created the layout for the wrap attached the models then produced the machining code.

The wood test pieces are 100 mm dia the layout was then increased to make 310 mm Portland stone bases to fit within a water feature.

Shell model:


layout:


Wrapped:

 

[Ollie78]

Yes you need to cut square to round on the 4th axis keeps it all true, to do something like the round bases you would start off making the 2 1/2D model you want to build with in my case i had made the shell for a set of drawers, I work in Vectric Aspire I created the layout for the wrap attached the models then produced the machining code.

The wood test pieces are 100 mm dia the layout was then increased to make 310 mm Portland stone bases to fit within a water feature.

Shell model:
View attachment 173060

layout:
View attachment 173058

Wrapped:

View attachment 173059

Thanks, I have vcarve pro so I think its the same in general except I can`t model the 3d shapes directly in it. Do you set Z zero to the spindle centre?
Sorry, didn`t mean to hijack the thread.


Ollie

 

[Sachakins]

I only managed to read some of the posts, not the enire thread and, being in a similar situation with 'everything needs to come through the front door', I will share my journey. The CNC machine was on my bucket list and, after a lot of research, I chose the 1010 Workbee to be my machine of choice. At that time there were 3 popular versions: Ooznest for the UK market, Openbuilds for the American market and Bulkman 3D for the Asian market but all 3 selling everywhere. It was a hard choice. I mainly chose Openbuilds because of the proved and tested American quality. The UK was great, even improved, but the price difference from USD to GBP was pretty prohibitive for me. Bulkman's was cheaper but I was hesitant to make such a purchase from them. This was also 2019 and since then Bulkman built a name for themselves.

Out of nowwhere, in 2020 a Workbee dealer appeared in the Romanian market. I contacted them, stated my interest in buying the CNC and got no reply for a long time. Eventually I managed to find out that they didn't have the actual machines, they were distributing the CNC routers sold by a company from Portugal, by the name of RatRig. I also found out that RatRig were innovators experienced in 3D printing technology, a group of passionate people who added CNC machines to their portfolio. Not only added it but, after consulting with the community, added their own improvements.

After researching into it, I ordered their version of the 1010 WorkBee CNC. Soon after my purcahse, they launched their own design of a much improved version of the WorkBee, this time with linear raild and steel plates, called the KillerBee. I was annoyed for not knowing about it but it was my fault since I wasn't following their community at that time. After much consideration and saving the money required, I purchased the upgrade kit for my machine. Soon after my purchase and now owning a superb machine, they launched their Stronghold Pro CNC which is 100% their design, concept, integrating feedback from the community as well. It was again my fault because now, even if I was following their community, I had not paid attention to their updates...

This Stronghold Pro machine might be a good candidate for your needs in relation to the stated conditions. Might be worth checking it out. This is the link to their machines Routers - CNC Machines and here is the version I was referring to Rat Rig StrongHold PRO CNC - Standard Kit

They have a great customer support. And they also offer very solid tables and other accessories for the machines. Further, they have a helpful community where you can find all info you need before making a purchase decision.

Merry Christmas and happy holidays!


Brad

That's quite normal, no sooner do you commit to one, then sods law kicks in and the upgrade comes out.

If you kept waiting for the next upgrade, you'd never get one!

 

[Phill05]

Do you set Z zero to the spindle centre?
Sorry, didn`t mean to hijack the thread.


Ollie

Yes Z zero centre, and me too sorry to take up part of thread.

 

[ToolsToday]

Thanks for the recommendation. I will see what they have in the new year. I have a 1 and 1/8" Amana surfacing bit that I like a lot but replaceable inserts would be an additional blessing.

Your wish is our command, Amana have many different sizes of insert surfacing bits available, the most of any provider globally. Check the range out here

 

[spiritburner]

I'm working in a Maker Space in West Yorkshire. In our 2024 budget we aim to have £3-3.5k set aside for a 3 or 4 axis cnc portal miller for wood cutting. Since we have multiple users of varying skill ranges we need a fair bit of rubustness built in and would like proper slideways and ballscrew drives. Assuming that extraction, bench and any shielding was covered by other budgets and we wanted to be able to cut at least a 750x750mm area what machine would you look at?

Onefinity
Shapeoke
Bulkman
any other

Based on that budget I would look at a Ratrig CNC or Openbuilds , I have both (in fact 3) but I prefer the Ratrig to Openbuilds although on my RR models I do use the BlackBox Controller from OB. Perhaps even think of a larger bed of 1metre by 1.5metre They are both very good machines, you can easily add to them if you want to in fact I have stiffened my latest RR machine to enable it to easily cope with Non ferrous metals and some mild steel work.

It will easily cope with all hardwoods but for working in wood you do not really need ballscrews, the accuracy of belts and carriages is fine enough for working with all types of wood and above a 1.5 metre bed its actually not recommended to go down the screw methods especially if you are just using Acme lead screws because of the Whip that is generated and although you can compensate for that to be honest its not worth the additional cost unless you are expecting an accuracy of 0.001 which would be highly unlikely for carpentry.

Belts are very fast and if correctly maintained you will not have any problems. Both OB and RR can offer Ballscrews, Lead Screws, Carriages and Belts, it just depends on your budget at the end of the day and the sort of accuracy you are looking for.

Look at Ooznest in the UK as they produce the Workbee which is normally made from OB extrusion and parts etc,

Ratrig make 2 models called Stronghold which in my opinion are superior to the Workbee models. you order direct from them they come with ballscrews and 20 mm linear rails, they also do cheaper models similar to the Workbee which run on belts and carriages which work fine.

I only went with a ballscrew because I do require that level of accuracy as I built it to use on Non Ferrous metals
If your going for a 3 axis machine you do not have to buy a 300 gbp controller you can use a Makebase one costing around 50 GBP with a touchscreen for basic offline work ,

The more expensive controllers do give you more functionality and on board stepper drivers upto I think 4 amps now which will easily do Nema 23's

For a 4 axis machine you will need a better controller however if funds dont permit this go for a cheaper controller and change it when funds permit, they are dead easy to retro fit and its easy enough to sell the older controller.

I would stick with GRBL over Mach 3, simply because the average maker is likely to be familiar with GRBL from using 3d printers , Plasma cutters and lasers and getting them suddenly to use Mach 3 would be very demanding.

Also Lightburn which is mainly GRBL is likely to have a full CNC version in the not to distant future which makes transitioning from lasers to CNC very easy if you already know the CAD/CAM software and in my opinion Lightburn is the best for lasers there is. I have used it now for around 10 years and its works flawlessly.

With a Makerbase controller you will need external stepper amplifiers which will cost around 30 GBP for 3 plus the driver shield to connect them which are around 5 GBP per stepper.

For working with wood you only need the standard Nema steppers and not servo driven ones which triple the cost.

For a spindle you can use a palm router such as the Makita RT0701C or Variants or there are cheaper ones around the 50 GBP mark but dont expect them to last the same time.

Personally I favour a VFD water cooled spindle but that will add considerable cost not only for the actual spindle and VFD but also the chiller to cool the water and while you can use a tank of water it is far safer and more practical to use the chiller especially where I am in Spain which I share with my C02 lasers.

Hopefully this has helped and if you need any further information please just get in touch. I build CNC machines, Lasers, Plasmas and large format 3D printers to order here in Barcelona.

I'm not looking for UK work so dont worry on that score, I have enough here to cope with.

Regards

Neil Scott
Pic is a recent laser build with a 50 watt C02, ( but extendable to 70) its different as the tube is on top which allows for more bed space with minimal loss of power for the additional optic.
I work with my partner who is based near Birmingham UK and he supplies the UK market and I do the European ones. We build to jointly shared developed plans that we make and have fine tuned over the years . Were both Engineers and currently are building a huge160 watt machine capable of a full size sheet.