My First CNC Machine

[murray]

Hello,
I have been reading these forums for a while, and have finally decided to start designing my first cnc machine. I plan on having a work envelope of 7 (X) by 6(Y) by 3 (Z). I plan on using it for PCB milling/drilling, carving foam, and carving soft wood/plastic. For the cutting tool, I will be using a cheap dremel tool with a flex shaft to reduce vibration. The frame will be built out of rectangular steel or aluminum steel. The leadscrews will be hardware store 1/4 inch threaded rod. The linear motion system will be 1/2" rod from the hardware store with bronze oil inpregnated bushings from Princess Auto. For the motors, I plan to use stepper motors from old printers. For the controller, I will use my own modified design (see my instructable here). I have made a model in sketchup and have posted it below. Tell me what you think.

My questions are: Is this going to be strong enough? Is it going to flex much? Will it be acurate enough? Is there anything else I need? Where can I find decent steppers for cheap (max $15 for all three)?

Please remember that I am 13, and there for can't afford $200 acme leadscrews, etc.

Thanks

[BobF]

Sounds like you need to scrounge all your parts. See if you can find an old printer to steel the motors from.

[dertsap]

if your going to be using threaded rod then i would suggest using 1/2-13 rod rather than 1/2-20 , you'll almost double your feed rate , finding steppers for less than $15 is slim to none , my son and i are building him a machine as well as adding on to my own so we know how it is to work on a budget , you meantioned Princess auto , I'm 10 minutes from the one in Coquitlam , so i'll tell you what , if you live in the Vancouver area , i have 3 50oz 24v steppers that you can have for $15 , if your interested then let me know , you and your Dad can come by and pick them up , i used them on my first build and they would be an ok motor to start with , other than that they will sit on the shelf for quite some time

this is the machine my son and i are building my router table

[murray]

Hello Again,
Thanks for the offer dertsap, but unfortunatly I am in Ontario. Your cnc is looking good. What size motors do you think I should try to find for a cnc of this size? Would printer repair store have cheap motors that would be big enough for this machine?

Thanks again

[dertsap]

you could look at places that do photocopy machine repairs , they may have some motors that were removed from scrapped photocopiers and they might be willing to give you the motors for a cheap price ,

[murray]

Hello,
I have decided to switch my design from steel to 5/8 MDF. I switched because I thought it would be easier to build. I am starting to cut the wood tonight. Should have some pictures soon.

[murray]

I started cutting the MDF tonight. I modified the design a bit. The first modification was that we mitered the corners of the wood. This makes it look better and gives it more strength. The second modification I made was that I put a solid base of MDF to give it more strength. I am posting of few pictures showing the pieces clamped together. I now need to buy some 1/2 inch steel rod for the linear rails, and then I need to take some of my wood to my Dad's school so that I can use the drill presses to make some strait holes.

[dertsap]

wow !
you don't mess around and get right to it , awsome job

[dertsap]

if you have a hard time finding motors then let me know , you can pay for the postage and you can have the three 50 oz motors i've got here , they are 24v 5 wire so they will only run unipolar and need high voltage , if they would work for you then they are yours , there are few kids that are willing to fulfill their time building these types of things instead of burning their mind on video games

[murray]

Hello,
I got some more work on my cnc done today. I went to my dad's school and used the drill press to drill some of my holes. I also found some 3/8" rod for my linear ways at the school. I have decided to make my bushings out of a nylon cutting board. Will this work well? I am still trying to figure out how I am going make my bushings. Hope to make some more progress over the easter weekend.

[murray]

I went to a photo copier repair store and they gave me two paper feeders off of photocopiers. I got 3 nema 17? motors. I attached some pictures of the motors labels. What kind of power supply should I use. Would an old computer power supply work?

I have also started to glue and brad-nail it together. should have some more progress tomorrow.

[BobF]

Murray,
Your motors say 2.9V 1.2A. If you look at other motors this gives you a point of comparison.
When you get a driver, you need to set your amps to 1.2 .
You can get a rough idea of torque by comparison. I would guess you have about 50 oz. in. torque. This should drive a small light machine.
Good luck.