Beginner MYCNCDIY Mill Build questions

[JAZZCNC]

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.!

[suraj1793]

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)?

[T0rnado69]

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.

[suraj1793]

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:

http://www.mycncuk.com/threads/1541-...-framed-router

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?

[suraj1793]

Did some more searching and found this (http://www.mycncuk.com/threads/5790-...tor-and-drives), in this post JAZZCNC also highlighted the fact that 3.8mH is slightly high for motor inductance therefore, my first question has already been answered (unless the inductance rating depends on the application?).

Therefore, I started searching again for available kits/equipment for the electronics part of this build and heres what I found:
Stepper Motors: As per recommendations in Ivars211's thread (http://www.cnc4you.co.uk/index.php?r...product_id=362)

PSU: This was a bit confusing. In JAZCNC's post it was highlighted that for best performance you should run the motors at around 60-70VDC however, the kit on ebay shows 2pcs PSU 350W (36VDC/9.7A) and the 3 axis kits for running 3.1nm steppers on CNC4YOU.com showed 1pc 400W (36Volts) PSU. Are the kit PSU's just making use of large safety margins for the supply? If so, should I be looking for a PSU rated at 60-70V and 8-9A? Does anyone have any recommended suppliers? (Will be looking into building toroidal PSU if necessary)

Drivers: As per the ebay kit (http://www.ebay.co.uk/itm/3Axis-Step...item2eca734c31) However, I just noticed that these are rated at 50V and as per recommendations in the post they should be rated higher than the maximum applied voltage (which is recommended at 60-70V) therefore, are these the wrong drivers? If so, are there any suitable alternatives which are in the same price range? The AM882 were a bit out of my price range for this first build however, seem like a very good upgrade for the future.

[Boyan Silyavski]

All depends on the size of the machine and the weight of the gantry. Then come the motors and so.

What working area??? What is the hardest material you will machine? How much money are you ready to spend on the build?

[suraj1793]

After much guidance and a lot of build log reading I think an achievable goal for my first build is to be able to machine wood (typically at around 40mm depth) and be able to do a lot of carving work (although if I can get more depth it would be preferred). If this could also engrave aluminium this would be a major benefit (although not my primary purpose for this machine).

Cutting area for this would be around 500mm x 500mm. Material and equipment for the frame (steel or aluminium box section, mig welder, drill press and hand tools) are all available for free from work. For the rails I was going to use roller carriages with a cold rolled steel plate as a guide rail and for the linear motion of the axis I was going to be using ACME threaded rod (but setup for later replacement with ball screw).

For the spindle I was thinking of initially going with a simple router like a bosch colt or maybe something smaller which I have already in the workshop such as a pnematic dremel but after some time upgrading to something like a 2.2kW spindle dedicated to the machine.

Budget for the electronics (motors, drivers, PSU) is around £200.

This build seemed to suit all my requirements therefore, I planned on using this setup as a guide: http://www.mycncuk.com/threads/1541-...-framed-router

This was another build I was looking at as an alternative but I am not sure if it would be powerful enough for what I need: http://www.neo7cnc.com/

Also, it may be worth mentioning that I also have an arduino uno available so was thinking of running this from GRBL as this would allow me to use my laptop USB for to communicate with the machine.