[3Dsigns]

I am planning to build a fairly large foam cutter using some 80/20 aluminum T-slot extrusions and other parts I have on hand. I also have some of 80/20's linear slides. I don't have much money to spend so, I was thinking that, instead of buying expensive linear rails, I would use the 80/20 extrusions as the rails and use the slides. These things slide surprisingly well and 80/20 also makes/sells "high-cycle" bearing pads for these units. http://www.8020.net/Images/Application-106.jpg I think that as slow as this thing will be, they should be sufficient. I'm not looking for absolute perfect accuracy anyway. like what would be needed for a router or mill. I would sure like some help in figuring out a few things on this.

What size stepper motors would I need?
Would a 3/4" timing belt be sufficient for the y axis?
1" belt for the x axis?
What type wire would I need?
As for a controller, I would like to maybe add a turntable later so would a 3 axis controller be fine? Or would I need 4? If I could just get the board/s, I can build the enclosure and install the components for it
I use SignWizard (Aries Graphics) to make most of my 2D vector files and have Aspire 2.5 for making 3D models and generating G-code: could Aspire run it or would I need Mac3?
I also plan to build the heat generator power supply thingy using a transformer and a potentiometer of some kind to control the heat. What size transformer and potentiometer would you recommend for a 7' or 8' wire length?


Oh yeah, as it is drawn here, the cut capacity would be about 120" x 84" x 66"H. I could cut down the height if I don't need that much, and it would most likely help prevent problems with racking. Does my design look like it would work?
?
Thanks!

[3Dsigns]

I reduced the height of the upright t-slot 'gantry' to 60". Aren't most foam blocks 48" high anyway? Then widened the base to 14". This would reduce the cut length to 113" but would make the uprights more stable.

What do ya think?

[3Dsigns]

sorry, double post

[bopierce]

Never used the type of linear guides you have chosen, but I can tell you if using bearing a nema 34 stepper with a gear box works well. Motor torque is not real critical when using gearboxes
As for as moving the axis’s with belts, why not? Chain would also be an inexpensive option.
I see 4 motors in your dwg, so you would need a 5 axis board if you are going to use a turn table
You can buy various types of wire for EPS from companies like alloy wire. Quick Google search will turn up a nice list.
As for as transformer size, that depends on the wire size. The bigger the wire the bigger the transformer.
Payne engineering sells a 30 amp SCR that’s ready to go. Don’t remember what we paid for the last one, but I don’t think it was much more than $300.00.
For a .014 nickel wire 30 amps is more than enough for 1 wire.
You are right about block size. The biggest I have ever seen is 50” thick. Any thicker the middle of the block does not fuse together well during molding.
Hope this helps

[3Dsigns]

Thanks!
Do I need gearboxes on the motors?

[bopierce]

Not necessarily
You are going to be cutting slow, prob around 20 inm for 1lb foam. The gear box will let you be closer to the middle of the motor rpm range with lot more torque. I always like to be in the middle of the rpm arrange of a motor instead at either the upper or lower range. Plus I like the extra torque.

[3Dsigns]

That makes sense. Sounds good. Thanks!

[3Dsigns]

Do I need my uprights connected at the top to counteract the tension of the wire, or do the y need to be able to move independently for taper cuts?

[bopierce]

That depends what you are trying to cut. If you are using 1 wire (tapered cuts), I would think you a good to go, But if you are looking for more of a production machine with 20 or 30 wires, then you need it really ridged. I have seen 2X3 aluminum tubing bend from trying to use too many wires.

[3Dsigns]

Thanks BoPierce

In light of the possibility that I might want to cut with more than one wire, I will try to design it so that a cross "gantry/brace" can be added or removed when needed. I have a few more questions...

Since my wire will be between 7 and 8' long, would this transformer/power supply work for me? If so, how many wires would it supply? LiteFuze LT-1500 1500 Watt Heavy Duty Voltage Converter Transformer Step Up/Down | eBay



I want 4 independent motors ont he x and y axes and a 5th axis so that I cna add a turntable/lathe at a later date. Would this be what I need to run the machine? or is 262 in/oz powerful enough? 5 Axis Driver Board + 24V PSU + 263 Oz-in Stepper Motor + Mach3 Software CNC Kit | eBay
Thanks

[bopierce]

I would think that that stepper set would be fine. You can always put some counter weight on the y axis if needed.
I not sure about the transformer. not really sure what you are trying to do. You need to use a SCR to control your voltage, Search on Ebay (Payne SCR). There is a really nice 50amp for 89.00. I might have to buy that one. It is a 240vac, but there is a little transformer on the board that can be rewired for 120vac if needed. You would need to buy a 75K ohm pot for it, but they are cheep.
I would think you could run about a dozen wires, prob more, (depending on the type of wire) with that Payne unit without a transformer.
Hope this helps

[3Dsigns]

Is it this one?
Are there other brands? Because I only see one like it on Ebay.
Thanks.

[3Dsigns]

I want to be able to cut through a very large block of foam to build monument signs, architectural moldings, and 3D letters . My machine will be over 10' long x 8' wide x 6' high. I'm thinking the wire length will be about 7' so it will need plenty of heat, especially if I add a few more wires for cutting miltiple sheets, moldings etc.

[bopierce]

50 amp Payne unit will do it. 1 of our cutters is 12' wide 6' high, and 16' long. we can put 40 wires (.014). we use a 150amp Payne unit and have had the same unit on it for over 15 years with no problem. we put 240vac to the Payne unit then run that thru a 2 to 1 step down transformer. this approx doubles the amps. For what you want to do I think that a 50 amp unit is more than enough.
This is the unit I was talking about: Item #300745926743

[3Dsigns]

Thanks Bo

[3Dsigns]

Bo,

I found some v groove bearings to run on my home-made rails which have room for a sturdy 3/8" axle/bolt. Lot/Package of 8 V Groove Ball Bearing 3/8" CNC Rails/Slide Guide Wheel 8 pieces | eBay

But these are much cheaper. Do you think they would be sufficient?

20pcs 4mm 624VV V Groove Sealed Ball Bearings 0.157'' Vgroove 4 x 13 x 6mm | eBay

[bopierce]

My thinking would be in your case bigger is better. You do want to build a fairly good size cutter. I have never built a cutter with V bearings so I might not be the one to really help you on that.

[3Dsigns]

I think i will go with the bigger ones.
Thanks!

[3Dsigns]

If I used this kit, where would I find gearboxes to gear them down? Is this a good deal, or does anyone know of a better price somewhere? Thanks!

5 Axis Driver Board + 24V PSU + 263 Oz-in Stepper Motor + Mach3 Software CNC Kit | eBay

[3Dsigns]

Or would I be better off with these steppers........

5pcs Nema 23 stepper motor 425oz-in 3.0A FOR CNC Cutting LONGS MOTOR | eBay

...and would these be the right components to go with them?
CNC Router DIY Kit 5 Axis Breakout Board + 5x M542H Stepper Motor Driver 1A-4.5A | eBay