I am trying to build the following machine (https://wiki.hackmanhattan.com/image..._eBook_1-4.pdf) which has a cutting area of 8.5" x 7.5" x 3". For my applications I require to machine hard woods for long periods of time and if possible in some very rare cases 10mm thick mild steel ran at very slow speeds for which bad precision and long machining time is not a major concern.
The question now is, what size NEMA stepper motors do I need to do this and is the frame suitable for my application? I saw within the document that the frame can be made to suit NEMA 23's, what size would be recommended and what controllers are recommended for this?
Please note that as this is a small low budget build, if possible I would try to keep the parts (motors and drivers) cheap (long lead times for part delivery will be OK). I have access to workshops, the time and material to manufacture the frame therefore, this should not be much of a problem.
Forget mild steel, that machine is too flimsy and spindle too weak to do more than scratch the surface. It'll struggle with any serious hardwoods but will probably manage mdf and ply ok and might be good for PCB routing. Watch the YouTube videos, it's struggling with mdf and feed rates are like watching paint dry. What are you planning to make that fits in such a small work area?
NEMA 23 3Nm low inductance motors (4mH or lower) - not because this machine needs them, but because they'll be reusable on the next one which is properly designed to meet your needs.
Last edited by irving2008; 29-10-2014 at 11:22 PM.
What motors to use are least of your troubles in all honesty. The fact this machine uses's threaded rod is a much bigger issue because this will severly limit the performance so which motors or drives/psu doesn't matter as the screw pitch will be the choker regards speeds not motor size.!
Feeds and speeds required for cutting hard woods will be outside of what this machine can reach due to tiny pitch of the threaded rod. Then you have the accurecy issue or lack of it from threaded rod. Combine this with known problems like wearing out the lead nuts which means your constantly chasing the machine and poor repeatabilty then your on hinding to nothing and much frustration.
Personaly I would look around at other designs and try to find some better cheap linear components like supported linear rails and ballscrews.
Thanks for sharing your knowledge and experience guys, you saved me from potentially wasting a lot of time and money.
For this build I have access to a car repair workshop (which also dismantles cars/vans) and a college workshop, both of which I can get free materials (such as steel frames supports, box section, sheet metal, etc) and equipment (such as mig welders, fasteners, power tools and hand tools) from and time is also not a major concern. I will continue looking for more rigid frame designs for this however, as I knew that both finding a decent frame and building it would take me a long time, I thought that I would be better off buying in the motors and drivers early on at a cheap price with huge lead times so that by the time the frame was towards being complete I would have everything ready therefore, if you know of such suppliers (cheap costs with long lead times) I would greatly appreciate it if you could send me a link. Also, any recommendations on cheap drivers?
I will look around for the linear components and frame design's, if anyone has any information or links to this please could you let me know. Or even better, if anyone knows of what these components could be salvaged from (ie home appliances or common equipment), I could possibly find that.
Also, as mentioned I will have access to complete cars and vans for any parts that can be salvaged from them for this build therefore, if you can think of anything that may be useful from these please could you let me know.
EDIT; Sorry, forgot to answer your question, I am using this to manufacture small extrusion dies for the end of a rubber extruded (only a 60mm diameter die with a machined profile within it) The larger size bed was really for small wood work hobby jobs. Could smaller size motors be used for such work?
Last edited by suraj1793; 30-10-2014 at 05:49 PM.
Cheap motors and drives will end up being expensive throwaways as they simply won't perform and you'll end up buying something decent in the end anyway.
Lets start with your extrusion die requirement. What material and what's the profile look like? I suspect you're approaching the problem from the wrong angle but lets not prejudge it.
Start on the last pages of a thread and work forward, that way you can usually see the finished machine first to see if it interests you.
ebay (Chinese sellers)
Spelling mistakes are not intentional, I only seem to see them some time after I've posted
Suraj let me just say that trying to build any CNC machine on the cheap never works.!! . . . . It always costs you more in the end.! . . .BUT . . . Trying to build one capable of cutting steel on the cheap is DOOMED from the beginning.
The best advice I can give you is STOP.!! . . . Don't do or buy anything as you simply haven't spent enough time doing the research that will be neccesary to achive building any CNC machine let alone one built on a budget for cutting hard materials. And I'm Not even meaning steel just the more dense Hardwoods or aluminium, Steel is a whole differant ball game which I suggest you forget for a first build.!
Go read most of the build logs to get some idea of just what's involved in building any machine. Read them properly not just flicking thru as you'll learn more that way.
Read every thing you can, then read some more and just when you think you have it sussed read it all again then come back with a design and we will start with the advise.
While doing this Save up your money and forget trying to build cheap it just never works out cheap in end.!
Thank you for all of the comments and suggestions, I have been reading up on build logs on both this forum and CNCZONE and only now am starting to understand the scale of the machine required to meet my manufacturing requirements and reading your comments/advice further confirmed this.
I will continue reading and researching CNC builds to gain a better understanding of what I need to do but would appreciate it if you could guide me on what is a "doable first build" so that I can base my research accordingly, I mean machining aluminium would be more than perfect for both my extrusion dies and so much more! but is this a practical goal for a first build?
I also learnt from your comments and other forum posts that with DIY CNC machines, cheap is BAD!!! But just to get a sort of indication of how much this build would cost me (machining aluminium) could you please let me know how much everything other than the frame (which I will be building myself) would be as an estimate (ie, steppers, drivers, power supplies, etc)?
this guys build thread here give a break down price of all the parts.
though its designed for woodworking and not ali.
but it gives you an idea.
Last edited by T0rnado69; 31-10-2014 at 12:25 AM.
The Following User Says Thank You to T0rnado69 For This Useful Post:
Since my last post i have read LOTS of logs and researched this topic in much more detail and think I have finally found something I think will be suitable for what I require:
ivars211 had started designing/researching this build also (http://www.mycncuk.com/threads/7412-...C-router-build) however, changed his design but did provide a lot of useful points and information.
I would try and use the mill for mainly wood work (40mm deep cut maximum) and some aluminium, my questions are:
- Is this machine setup suitable for my requirements?
- Ivars211 in his thread initially wanted to go for this kit (http://www.ebay.co.uk/itm/German-Shi...MakeTrack=true) however, was warned against it due to the high motor inductance (3.8mH). I am not sure if he used this kit however, in the thread it was recommended to use something at or less than 3.5mH. Would 0.3mH really make that big of a difference? This seems like a great price but not sure if I would be buying bad quality stuff if I went for it.
- For this build would it be suitable to use a roller carriage type setup for all linear carriages as shown here (http://www.cncrouterparts.com/linear...ent-p-100.html) with cold rolled steel as the guide rail? Would the machine still be fairly accurate?
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