DIY CNC machine on the cheap!

[imbaine13]

what type of motor will you use?

Here it is. It has been gathering dust as you can imagine! Tiny, I know, but I'll upgrade to a bigger one later.

By the way, I couldn't come up with a way of triangulating the gantry from the outside using one of the Y-axis rails, so I decided I'd continue with the piece of timber between the rails as the final design. I hope it works. I'm glad all those issues were ironed out before I started construction though.

Thanks for all you input, guys.

Looking forward to start building.

[wizard]

It looks like you are well on your way to a nice machine.

About that mention of getting materials cut to size, I wasn’t thinking about the factories but rather your local lumber yard. Around here anyways most lumber yards have some sort of panel saw to cut sheet goods. Just a thought.

As for wood warping that can be a big issue if you live in an area where the humidity varies drastically. Sheet goods like plywood will minimize the distortion but even sheet goods can be impacted. Honestly I’m a big fan of steel in machine construction so I’m on your side there. Generally though we are talking about steel with larger cross sections. Even with that consideration it looks like your current design is closer to workable.

I need to add that die grinders or more specifically Dremel like tools, don’t last long on CNC machines. That brand might be better but I really don’t believe it is that much better. The grinder will get you started but expect a need to upgrade rather soon afterward.

[routalot]

This is a very rough outline of the way in which I believe you could triangulate your gantry.The lower end could be held by a through bolt,similar to the other intersections and at the top of the diagonal brace you can saw a couple of straps from a piece of the box section and through bolt them.All you would need to do is extend the upper rail,but of course you could also extend the lower rail too.

[skrubol]

The blue Z rails hang below the rest of the carriage that rides on the gantry. I think this will be the limitation of your part height. I would raise it to be at the same height as the bottom of the carriage. The Z plate will need to be extended downward for your spindle to reach low enough. Alternately, you may be better off with the rails attached to the Z plate and the bearings on the gantry carriage. That seems to be the arrangement most routers with a lot of Z clearance use.

[imbaine13]

Hello guys!

Hope you've all been good!

I apologise for the delayed response, work and family got in the way the last few days.

It looks like you are well on your way to a nice machine.

Glad to hear that! I'm looking forward to finishing it!

About that mention of getting materials cut to size, I wasn’t thinking about the factories but rather your local lumber yard. Around here anyways most lumber yards have some sort of panel saw to cut sheet goods. Just a thought.

We do have those, but it's too much of a hustle getting the parts over there, having them cut up and finally ferrying them back to the workshop! Most of the time, there's long queue!

As for wood warping that can be a big issue if you live in an area where the humidity varies drastically.

Incidentally, that's exactly where I live, which is why I decided to totally avoid that path!

I need to add that die grinders or more specifically Dremel like tools, don’t last long on CNC machines. That brand might be better but I really don’t believe it is that much better. The grinder will get you started but expect a need to upgrade rather soon afterward.

Understood. I'm really not sure whether or not it's better than a dremel. At the time I bought it, the cheapest I could get a dremel around here was $140 and this only cost me $40!!! I know for sure a dremel is better, but I can't tell by how much. This particular brand does feel sturdy and reasonably well built though. Runs smooth, not too loud. It should work during the CNC familiarisation phase, after which I'll upgrade to a bigger router.

Isaac

[imbaine13]

This is a very rough outline of the way in which I believe you could triangulate your gantry.The lower end could be held by a through bolt,similar to the other intersections and at the top of the diagonal brace you can saw a couple of straps from a piece of the box section and through bolt them.All you would need to do is extend the upper rail,but of course you could also extend the lower rail too.

That's exactly how I had done it. Only, I extended the lower rail! Here's where I had problems! I failed to come up with a simple means of connecting this joint, but after considerable thought, I figured whatever method I came up with would beat using the piece of wood, so here's how I did it.

[imbaine13]

The blue Z rails hang below the rest of the carriage that rides on the gantry. I think this will be the limitation of your part height. I would raise it to be at the same height as the bottom of the carriage. The Z plate will need to be extended downward for your spindle to reach low enough. Alternately, you may be better off with the rails attached to the Z plate and the bearings on the gantry carriage. That seems to be the arrangement most routers with a lot of Z clearance use.

Hello skrubol,

I observed that a while ago but it didn't bother me much at the time because I was constantly distracted by other parts of the machine. It wasn't until I measured the clearance after your mention of it (a little less than 50mm (~2")) that I thought something had to be done! I intend to have a 75mm (~3") Z travel, so if I were working on a surface that was say 65mm above the table surface, the Z-rails would definitely hit the work piece if it got in the way. I did some last minute revisions and managed to raise the rails 85mm above the table surface. Thanks.

Isaac.

[imbaine13]

Alright,

So here's Rev 3! I was a little concerned about the X-axis rails sagging under the weight of the gantry, so i added some 1mm x 50mm (cross section) metal strips (green) along them. I hope this is good enough to allow extension of the X- axis if the need arises. These metal strips are impossible to bend in that orientation, which should guarantee rigidity along the X-axis rails. They also serve a second purpose of shielding the X-axis against debris from cutting so the linear assembly doesn't jam up. I shifted the wooden table away from the frame in one of the pictures so the attachment is easier seen.

[routalot]

That's exactly how I had done it. Only, I extended the lower rail! Here's where I had problems! I failed to come up with a simple means of connecting this joint, but after considerable thought, I figured whatever method I came up with would beat using the piece of wood, so here's how I did it.

Put simply,your proposal will prevent the upper portion of the gantry lozenging.Mine will prevent the whole upper assembly moving.Combining the elements of both could be a good way to go.

[imbaine13]

Put simply,your proposal will prevent the upper portion of the gantry lozenging.Mine will prevent the whole upper assembly moving.Combining the elements of both could be a good way to go.

I see and understand what you mean, but I think for such a small machine, the 4 upright pieces of steel onto which the Y-axis and whole gantry assembly are attached should be more than enough to resist any tendency to bend sideways. But just in case, I attached a few images of what you mean. After looking through this guy's blog (https://homofaciens.de/technics-machines-cnc-v0-5_en.htm), I'm pretty sure either design would work. This guy has made several CNC machines, starting out with a simple one and evolving his design until he made a relatively decent one out of steel box section! I was impressed when he demonstrated that even machines made of particle board could cut aluminium (not very accurately, but with acceptable results), using the most primitive linear slide designs you could think of!!! And to top it all off, he ONLY uses hand tools (with the inevitability of a drill press). He also does some tests to check how accurate the machines turn out. I think he actually tried making one out of cardboard, but it was probably just a proof of concept for his final design. Watch his videos, you will most definitely enjoy them.

His experimental machines given me plenty of confidence in my design! I learnt a lot from his experiences and I highly recommend his videos.

Parts should be arriving soon! Eagerly waiting.

Isaac.

[routalot]

The latest evolution of your machine looks very promising.Thanks for the link to another home builder,it was illuminating to see what he achieved.I would advise caution about going the same way with threaded rod,it will work reasonably well while the wear on the threads is minimal,but is doomed to become less accurate as wear sets in.After all,the threaded rod is usually intended as a fastener and in that situation a nut is only run over the surface once.In the early days of home CNC there were several solutions involving jamming two nuts together to minimise backlash and some used plastic threaded blocks to spread the load.I suggest keeping a stock of threaded rod on hand.

[imbaine13]

The latest evolution of your machine looks very promising.

I'm glad. I have you guys to thank for that. The guy at the Post Office told me to check this week for the parts I'm expecting. I'm hoping to get most of them before the week ends so I start building during the weekend.

I would advise caution about going the same way with threaded rod,it will work reasonably well while the wear on the threads is minimal,but is doomed to become less accurate as wear sets in.

I came across some promising threaded rod early last year at the hardware store whose threads were very deep and well cut. If they still stock it, I'll give it a try although the pitch was low, so the machine will be a bit slow at the start. I was planning to use HDPE for the lead screws but I will upgrade to ACME screws and nuts eventually. I will experiment with the machine as much as I can before I start with the improvements.

Out of curiosity, have you logged any machine builds on the site? I'd love to take a look. Even if it's just pictures of the finished machines.

Isaac.

[cyclestart]

I've been following this thread and admire your determination.
Those green gussets could be used several other places in the design.
What ties the main frame and cross members together ? It's not obvious in the drawings but maybe you mentioned it elsewhere.

[imbaine13]

Hello cyclestart,

I've been following this thread and admire your determination.

Thanks, easier to correct problems now than much later during construction! I wanted to make sure everything would fit together. With the help of the community, I think I've arrived at the final design for the components I'll use.

Those green gussets could be used several other places in the design.

This could probably be done as a final step to strengthen areas that would require reinforcement.

What ties the main frame and cross members together ? It's not obvious in the drawings but maybe you mentioned it elsewhere.

I actually hadn't mentioned it. I will use these corner brackets. Btw, they are also great as guides for a hacksaw blade when cutting the steel by hand. I hadn't included them in the drawing because I was sure they would work.

Isaac.

[imbaine13]

Doesn't seem like the photo uploaded!
Here it is.

[routalot]

I'm glad. I have you guys to thank for that. The guy at the Post Office told me to check this week for the parts I'm expecting. I'm hoping to get most of them before the week ends so I start building during the weekend.



I came across some promising threaded rod early last year at the hardware store whose threads were very deep and well cut. If they still stock it, I'll give it a try although the pitch was low, so the machine will be a bit slow at the start. I was planning to use HDPE for the lead screws but I will upgrade to ACME screws and nuts eventually. I will experiment with the machine as much as I can before I start with the improvements.

Out of curiosity, have you logged any machine builds on the site? I'd love to take a look. Even if it's just pictures of the finished machines.

Isaac.

I have only built one machine from scratch and it is mentioned in this thread https://www.cnczone.com/forums/diy-c...-software.html .It was a learning tool for me as I have programmed and operated four commercial machines,a couple of them 5 axis,and liked the idea of having some of the same capability for my hobby workshop.I didn't intend to build a huge and rugged machine until I was satisfied that i had the ability to make a machine move correctly.Now I have a working tiny machine, I have to admit to a hankering for something a bit bigger.

If I do build another it will probably have supported round rail and a proper spindle,rather than a router for reasons of noise and power.I would stick with Chinese ballscrews and would prefer my steppers to have a larger shaft than the current version's 1/4 inch although they have ample torque.

[imbaine13]

I have only built one machine from scratch and it is mentioned in this thread https://www.cnczone.com/forums/diy-c...-software.html .It was a learning tool for me as I have programmed and operated four commercial machines,a couple of them 5 axis,and liked the idea of having some of the same capability for my hobby workshop.I didn't intend to build a huge and rugged machine until I was satisfied that i had the ability to make a machine move correctly.Now I have a working tiny machine, I have to admit to a hankering for something a bit bigger.

If I do build another it will probably have supported round rail and a proper spindle,rather than a router for reasons of noise and power.I would stick with Chinese ballscrews and would prefer my steppers to have a larger shaft than the current version's 1/4 inch although they have ample torque.

Wise approach! You are waaay ahead of me. Some day, I'm sure to catch up though. Seems to me like most people build their first machine to sort of learn how they'll build the second one. But primarily to use the first one to build a second. I initially had the same idea but wasn't sure whether 600 x 300mm cutting area would cut it (pardon the pun). Ironically, when I first thought off building a CNC router, I decided on one made out of MDF, but after recalculating, weighing a lot of factors and noticing how great the metallic machines looked, I settled for a steel fame. Now, I find even the lousiest MDF machines really appealing again!! It's too late for that now. They each have their pros and cons, but I now realise that I wouldn't mind using this prototype to build a second machine out of MDF if necessary.

[imbaine13]

Right! Been busy with work for the last few weeks. Meanwhile, some of the items I ordered arrived! There's still a few that I haven't received yet, but I guess they will eventually arrive in due course. I also had time to scrutinize the design and realised I tried so hard to avoid precision drilling, I totally forgot about precision cutting. So, I made further modifications. I did away with horizontal square tubes that run underneath the table in the Y direction because they maintained parallelism between the X-axis rails, and therefore had to be preciously the same length. I simply doubled the X-axis rails on each side so the inner square tube could be bolted to the paralleling tubes running across with room for adjustment. The images will make this easier to understand. In so doing, I had lower the gantry's lower horizontal support to create room for the modifications. I also did away with the vertical square tubes between the Y-axis rails for the same reason and replaced them with horizontally running square tubes. Much easier to set up and automatically keeps the Y-axis rails parallel. I completely redid the Y-axis carriage so I could easily preload the bearings against the Y-axis rails by simply adjusting the nuts. With this set up, both the Y and Z axis bearings can be preloaded without the need to dismantle anything. So, no need for precision drilling or cutting! I know this this thing is going to turn out really heavy, but if it does the job, I couldn't ask for anything more!

[imbaine13]

ABEC 5 skate bearings from ebay ($3 for 10 pieces)
Made an improvised 90 degree miter cutting jig for cutting the steel square tubes at right angles. I simply used 1.25" L profile steel lengths for this.
In some photos, you'll notice a piece of the 25mm x 25mm x 2mm square tubing I intend to use.
I also managed to score some 200 bolts and washers from the local hardware store.

[imbaine13]

Thought I'd give the metal parts an actual metallic finish. Turned out great!