CNC from scratch, need help.

[floodx]

Hello everyone!

I have been lurking these forums for a while now and now I think I am ready to get started. I have a rough design started in my head, but I ultimately want to detail the whole thing in a CAD program. Before I get started, I would like some advice on certain topics from people more knowledge about them than myself. This thread will also serve as my build log and a means of keeping track of materials, links, prices, etc.

I will share a little background info with you all so you have a better idea of my capabilities. I have never undertaken a project of this magnitude before, nor have I any experience with woodworking or machining. What I do have going for me is theoretical knowledge. I am in the last year of a mechanical-based engineering degree (naval architecture), so I understand that lingo fairly well. Like I stated previously, I also have been lurking these forums for a while. I have picked up some CNC-specific lingo since then (ex. backlash), but I am sure I am ignorant to a lot yet.

My requirements are as follows:

1. Low Cost (<$500, including motors)
2. Approx. 1' x 2' cutting area
3. Maximize Z-travel
4. Accurate to at least 0.1mm

Based on these requirements, I have come up with some ideas on what I would like for each part of the build.

Construction Materials
First choice: MDF (local Home Depot or Kent ~$10/sheet)
Alternative: Aluminium Angle (local Home Depot or Kent ~$5/3ft(?))

Linear Rails
First Choice: Skate bearings bolted to aluminium angle, running on aluminium angle.
Alternative: Skate bearings bolted to aluminium angle, running on a metal rod.
(http://www.vxb.com/page/bearings/PROD/Kit239 $9.95)

Power Transmission
First Choice: ACME Lead Screws (2 x http://www.use-enco.com/CGI/INSRIT?P...PMAKA=328-2767 $24.90)
Alternative: Allthread Rod (local home Depot or Kent)

Motors, Drivers, Controller, etc
First choice: A 3-axis kit from ebay (http://www.ebay.ca/itm/3-Axis-NEMA-2...#ht_6187wt_905 $184.88)
Alternative: A 3-axis kit from Keling (http://www.kelinginc.net/ThreeXCNCPackage.html $379)

Thoughts on the above would be appreciated, but I am more concerned with a few other issues.

First, if I use MDF, what is the best way to make joins? Cross dowels seem to be the most obvious choice to me, but Enco does not seem to carry them. Since I will (most likely) be ordering ACME lead screws from them and I do not want to place multiple online orders, this eliminates cross dowels from the running. Although, I am intrigued by what I have seen here: Step 2: Making the Connection, joint and would like to know if anyone can recommend that sort of join.

Second, I would like this CNC machine to be able to machine parts for my next CNC machine. Since my next one will likely be made from aluminium, I would prefer if this machine could handle that. Is this reasonable?

Third, metric vs standard? Given that I live in Canada, I obviously follow the metric system. However, cheap bolts, MDF sheets, aluminium angle, acme lead screws, etc are all imperial. Since I prefer not to mix and match (or convert everything to metric), I will probably just stick with imperial. Thoughts?

I'm sure I have countless more questions running around in the back of my mind, but these seem to be what is stopping me from finalizing a design.

[louieatienza]

Originally Posted by floodx Hello everyone! I have been lurking these forums for a while now and now I think I am ready to get started. I have a rough design started in my head, but I ultimately want to detail the whole thing in a CAD program. Before I get started, I would like some advice on certain topics from people more knowledge about them than myself. This thread will also serve as my build log and a means of keeping track of materials, links, prices, etc. I will share a little background info with you all so you have a better idea of my capabilities. I have never undertaken a project of this magnitude before, nor have I any experience with woodworking or machining. What I do have going for me is theoretical knowledge. I am in the last year of a mechanical-based engineering degree (naval architecture), so I understand that lingo fairly well. Like I stated previously, I also have been lurking these forums for a while. I have picked up some CNC-specific lingo since then (ex. backlash), but I am sure I am ignorant to a lot yet. My requirements are as follows: Low Cost (<$500, including motors) Approx. 1' x 2' cutting area Maximize Z-travel Accurate to at least 0.1mm Based on these requirements, I have come up with some ideas on what I would like for each part of the build. Construction Materials First choice: MDF (local Home Depot or Kent ~$10/sheet) Alternative: Aluminium Angle (local Home Depot or Kent ~$5/3ft(?)) Linear Rails First Choice: Skate bearings bolted to aluminium angle, running on aluminium angle. Alternative: Skate bearings bolted to aluminium angle, running on a metal rod. (30 Bearing 608ZZ 8x22x7 Shielded Grease Miniature Ball Bearings $9.95) Power Transmission First Choice: ACME Lead Screws (2 x Enco - Guaranteed Lowest Prices on Machinery, Tools and Shop Supplies $24.90) Alternative: Allthread Rod (local home Depot or Kent) Motors, Drivers, Controller, etc First choice: A 3-axis kit from ebay (3 Axis NEMA 23 Stepper Motor Driver CNC Kit + Software | eBay $184.88) Alternative: A 3-axis kit from Keling (Page Title $379) Thoughts on the above would be appreciated, but I am more concerned with a few other issues. First, if I use MDF, what is the best way to make joins? Cross dowels seem to be the most obvious choice to me, but Enco does not seem to carry them. Since I will (most likely) be ordering ACME lead screws from them and I do not want to place multiple online orders, this eliminates cross dowels from the running. Although, I am intrigued by what I have seen here: Step 2: Making the Connection, joint and would like to know if anyone can recommend that sort of join. Second, I would like this CNC machine to be able to machine parts for my next CNC machine. Since my next one will likely be made from aluminium, I would prefer if this machine could handle that. Is this reasonable? Third, metric vs standard? Given that I live in Canada, I obviously follow the metric system. However, cheap bolts, MDF sheets, aluminium angle, acme lead screws, etc are all imperial. Since I prefer not to mix and match (or convert everything to metric), I will probably just stick with imperial. Thoughts? I'm sure I have countless more questions running around in the back of my mind, but these seem to be what is stopping me from finalizing a design.

Instead of using round nuts (or barrel nuts, or dowel nuts, whatever they're called) and you have some router skills, you could simply rout a slot in which a square nut can fit in (with a little bit of chisel work), which would be infinitely cheaper; depending on the size of your fasteners this could be a blind slot (not going through) which would look more "finished" as well.

Being here in the US, I'm partial to Imperial measurements, but it really doesn't matter as your controller software can switch back and forth. Also, over here, metric nuts, bolts, etc. are very expensive relatively.

As far as milling aluminum, there are a lot here who do it with mdf machines, though it comes at a cost of speed. Obviously, mdf is nowhere near as ridgid or heavy as aluminum or steel, so your cutting forces have to be kept relatively low; meaning you should use the most powerful spindle you could afford. You might have to add additional reinforcements or double-up here and there. It might also be better to use clear framing lumber where you think you need a larger cross section.

As for your linear rail system, I think using round rails would be the most fiorgiving and easier to adjust, after experimenting with other configuratiions (flat bar, angle rails).

I used the Solsyva.com plans for my first machine, and it worked out well. Even if you don't buy the plans you could get some ideas howhis machines are put together.

[doorknob]

Originally Posted by floodx Motors, Drivers, Controller, etc First choice: A 3-axis kit from ebay (3 Axis NEMA 23 Stepper Motor Driver CNC Kit + Software | eBay $184.88)

Some people report success with that driver while others have had problems.

You might be interested in reading the following thread, if you haven't already:

http://www.cnczone.com/forums/genera...y_chinese.html

[grumpygeek]

I have built a few machine now, so I can add a little bit to the discussion.

Have you looked at these guys for controllers: eBay My World - modularcnc they are out Canada and seem to have an interesting range of products. I have a friend using one of their controllers without issue, I also have one but I haven't had the time to play with it.

I usually get cross dowels from here: woodpeck.com - cross dowels, you'll pay through the nose at a depot from them.

I have had mixed results with Enco for acme screws, the first set I ordered was very nice and required almost no clean up, the next batch was very rough and took a couple hours of cleaning, sanding and polishing to get to usable condition. Hope you get a good set.

How much Z axis travel are you looking to have, what are you planning in using it for? I only ask since this is a place where a lot of flex can be introduced.
My current machine only gives me about 2" above the spoil board, but I figured that was all I was going to need since I usually only cut .5" to 1" sheet products.

All 3 of my builds have used skate bearing on drill rod (set into mdf) or gas pipe and I am happy with the results. I just purchased a box of 1000 skate bearings from VBX, so obviously I am happy with them You can see my stuff here: grumpygeek.com, I am also planing on selling kits, but I am running a little behind on my product launch: bootstrapcnc.com.

Good luck with the build, if you are like most people this is just the beginning

[cyclestart]

Originally Posted by floodx Second, I would like this CNC machine to be able to machine parts for my next CNC machine.

If possible buy the drivers/motors/power for the next machine now, buying stuff twice doesn't save cash in the long run. Otoh if the details of the next machine are undecided it's hard to know what parts would be optimal.

Third, metric vs standard?

If the Big 3 automakers got away with mix-and-match so can we. My old British motorcycles have every thread form known to man except metric lol. Seriously I source as much stuff locally as possible. Half or more of my hardware comes from agricultural supply stores because farmers are cheap b****ds like me. (j/k farmers and thanks for the food)

[floodx]

Originally Posted by louieatienza Instead of using round nuts (or barrel nuts, or dowel nuts, whatever they're called) and you have some router skills, you could simply rout a slot in which a square nut can fit in (with a little bit of chisel work), which would be infinitely cheaper; depending on the size of your fasteners this could be a blind slot (not going through) which would look more "finished" as well.

I will look into this as an alternative. I am not too concerned with looks, so I may just stick with the method in the video I posted to keep things simple.

Originally Posted by louieatienza Being here in the US, I'm partial to Imperial measurements, but it really doesn't matter as your controller software can switch back and forth. Also, over here, metric nuts, bolts, etc. are very expensive relatively.

Metric are expensive here as well. They seem to be the specialty bolts.

Originally Posted by louieatienza As far as milling aluminum, there are a lot here who do it with mdf machines, though it comes at a cost of speed. Obviously, mdf is nowhere near as ridgid or heavy as aluminum or steel, so your cutting forces have to be kept relatively low; meaning you should use the most powerful spindle you could afford. You might have to add additional reinforcements or double-up here and there. It might also be better to use clear framing lumber where you think you need a larger cross section.

That makes sense. I have already considered reinforcing sections that would be more susceptible to bending. I was also hoping the bolted connections would help keep things together better as well.

I debated building it out of aluminum angle rather than MDF in hopes it would be sturdier. However, I ultimately decided that MDF would be easier to work with (which is important for someone with no practical experience in this sort of thing). That being said, I am considering reinforcing it with aluminum angle. I am considering doing this by bolting strips to parts that will likely flex under high loads (ex. vertically on the sides of the gantry). Hopefully some innovative designing will allow these reinforcements to act as a torsion box as well.

Originally Posted by louieatienza As for your linear rail system, I think using round rails would be the most fiorgiving and easier to adjust, after experimenting with other configuratiions (flat bar, angle rails).

Round rails do seem like the best options, but I have not been able to incorporate them into a design I like yet. We will see what happens I guess.

I have done some more research into round rails and limiting their flex will make the design more complicated than I would like. With aluminum angle I can support them using the edge of the MDF (although I am not sure how to taper the edge since I will not have a router at this stage).

Originally Posted by louieatienza I used the Solsyva.com plans for my first machine, and it worked out well. Even if you don't buy the plans you could get some ideas howhis machines are put together.

Thanks, that site has great information aside from just plans!

Originally Posted by grumpygeek I have built a few machine now, so I can add a little bit to the discussion. Have you looked at these guys for controllers: eBay My World - modularcnc they are out Canada and seem to have an interesting range of products. I have a friend using one of their controllers without issue, I also have one but I haven't had the time to play with it.

Ideally I was looking to get everything as a kit, but I am open to buying the components separate if the price is right. I will keep this source in mind.

Originally Posted by grumpygeek I usually get cross dowels from here: woodpeck.com - cross dowels, you'll pay through the nose at a depot from them.

If the shipping costs are reasonable, I will consider buying cross dowels online. Thanks for the source.

Speaking of which, can I get parts from Fastenal sent to a local Fastenal store and avoid shipping costs altogether?

Originally Posted by grumpygeek I have had mixed results with Enco for acme screws, the first set I ordered was very nice and required almost no clean up, the next batch was very rough and took a couple hours of cleaning, sanding and polishing to get to usable condition. Hope you get a good set.

I assumed I would have this problem if I went for cheap acme screws. I am just hoping I have the skills to actually clean them up rather than make them worse.

Originally Posted by grumpygeek How much Z axis travel are you looking to have, what are you planning in using it for? I only ask since this is a place where a lot of flex can be introduced. My current machine only gives me about 2" above the spoil board, but I figured that was all I was going to need since I usually only cut .5" to 1" sheet products.

I would like to be able to cut foam R/C boat models with my machine. My biggest problem with doing this is I have never actually worked with R/C boats before. I am not even sure what sort of dimensions to be aiming for. I am thinking somewhere between 4" to 6" (I would mill each half of the model separate and glue them together after).

Originally Posted by grumpygeek All 3 of my builds have used skate bearing on drill rod (set into mdf) or gas pipe and I am happy with the results. I just purchased a box of 1000 skate bearings from VBX, so obviously I am happy with them You can see my stuff here: grumpygeek.com, I am also planing on selling kits, but I am running a little behind on my product launch: bootstrapcnc.com. Good luck with the build, if you are like most people this is just the beginning

For my first (crude) build, I am confident (/hoping) the skate bearings will be fine.

Thanks for the link to your site. It looks like a great resource for someone such as myself.

Originally Posted by cyclestart If possible buy the drivers/motors/power for the next machine now, buying stuff twice doesn't save cash in the long run. Otoh if the details of the next machine are undecided it's hard to know what parts would be optimal.

I was thinking the same thing. I am aiming for ~280 oz-in motors because I feel they are overpowered for what I am building. However, I am afraid they may be underpowered for my next project (since I do not know how big it will be).

Originally Posted by cyclestart If the Big 3 automakers got away with mix-and-match so can we. My old British motorcycles have every thread form known to man except metric lol. Seriously I source as much stuff locally as possible. Half or more of my hardware comes from agricultural supply stores because farmers are cheap b****ds like me. (j/k farmers and thanks for the food)

Yeah, that is why I am trying to limit online spending to the ACME screws only (and the reason I am still considering all thread rod).