I have bought the 10A board and contacted Hector, so I'll see how this goes and update y'all. I'll use the 2.5A NEMA 23 motor I got for the X-axis -- I bought nice strong hex socket cap screws and nylon locking nuts and big washers for mounting it -- the MDF is showing a few signs of wear.

Here's a synopsis of what happened:

I am cutting 2" thick x 2' x 8' foam sheets, and the X-axis stepper motor is under a bit of stress. I was losing steps until slowing the feed rate down to ~25"/minute, and cutting in 1" deep passes.

I did a number of trial runs, and then got 1 sheet cut. Then on the next sheet (a week or so later) the X-axis was moving only half of what it was supposed to. Mark had recommended using a 2.5A NEMA 23 stepper on the X-axis which I had then bought, so I decided to install it to see if that was the problem.

The stock 1A NEMA 23 stepper was quite warm when I took it out (even though the power was off) and after I put in the 2.5A unit, it pulsed about 2-3 times and the fuse blew.

I put the stock motor back in, and again the fuse blew almost immediately. So, Mark sent me a replacement chip.

I swapped the chip, and the socket cracked on one corner when I put in the new chip. I crossed my fingers that it would work anyway, but the fuse blew again (3rd time).

So, I have ordered the 10A driver board (a few minutes ago) and I will hopefully be cutting foam, soon!

 

Neil, I'm not a big fan on the CNC board and had to change my x-axis chip to a high temp one but I have to say that I don't thing that the problem you have is the amps of the board. I run on the x and the y axis a motor that is rated at 3A. I had it set on the CNC board to about 2.6A. I had cut a part that took 10hours to cut, non stop, and I had no problem with the board. What I'm saying is that you may have a bad part on your board, that neither you nor I can tell which one it is, that is causing the problem. Ask Mark if your board is still under warranty and send it to Hector. If he fixes it you'll have a spare one.

 

Yes, I will have to send it in for repair. Because the 10A unit is not in stock at the moment...

 

Well, I ordered a new 2.5A driver board yesterday, and hopefully it arrives tomorrow. I'll see about getting the one I have repaired. I will use it to test the X-axis motor and the higher torque motor I got; using the Y or Z channels.

 

Which board did you get? The EasyCNC? If not, can you post a link? :questions:

 

Yes, the EasyCNC 2.5A model that comes with the PhlatPrinter 3.

Edit: It is due to arrive Monday. Which okay (I guess) since I am working for a client on Saturday.

 

My new 2.5A Easy-CNC board arrived this morning, and we have power, so hopefully I can swap it -- after I cut up a bunch of downed tree limbs!

 

Okay I tested both the original X-axis stepper motor and the new higher torque unit on the old driver board, and the new motor blew the fuse after a about 30 seconds of operation, and the original unit seems fine.

So I've installed the new Easy-CNC driver board and all seems well. I think the g-code I made of the revised layout had the error I was seeing in the X-axis, so I am about to redo the g-code file and then try to cut the sheet.

Wish me luck!

Edit: I am not getting the correct results, still! The X-axis is "compressed" to only half of what it should be and the Z-axis also seems to be not deep enough. I have it set up for 1" deep passes but it goes in about 1/4".

Something is not jibing between the settings file that I've downloaded, and then changed the settings that I need for the sheet size and thickness, and I've rechecked my G-code settings in the Phlat Tools plugin in SU.

Aaarrgg -- can someone please help me figure out what is going wrong?

 

Here's what I'm seeing after loading the G-code, and notice the large set of lines that are waaay outside the 2'x8' sheet:

 

Okay, I re-made the G-code without the tabs and all is well. Except those large lines are still there. Maybe there is a bug when tabs and multipass is used at the same time?

But it more or less, cut the sheet with minimal skewing -- the bit must be getting dull(er) and so at the end there was a bit more cotton candy forming. I pause the program and lift the Z-axis and clean it off. Is this what the bit changing tool is for? I didn't want to try it and get messed up.

I really think I need to buy a longer bit that can cut clear through in 1 pass and use tabs. I was able to cut all but a 1/16th or so which works fine except that the gap can be squeezed down by the side rails.

 

Neil, I use the multipass with tabs and have no problems with it. I cut 3/4" bass wood with thirty something passes and the tabs are the last ten or so passes.

I ran into the same problem with the rail squeeze as you. After I've cut one part on the sheet it started to skew into the gap created by the cut of the first part.

 

Well, for whatever reason, the new g-code works, and the X-axis compression was caused by the code, and not the driver board. The problem with the driver board was caused, apparently, by the higher torque stepper motor.

I'm getting a quote from a local company for 5 bits with 2"+ cutting edge and a ball tip and an overall length of ~2.75". They will likely be about $100 each, and they can be sharpened, so I can cut all ~45 sheets of foam clear through (I'll use tabs!).

 

I don't know why you wouldn't use the hot knife from Michael's that someone posted here before. Definitely cheaper than the bits. By far.

 

what's the smallest diameter drill bit with a 2'' cutting length?

 

Setting up a hot knife would be a lot more work with trial and error refinements. And you cannot do 3D carving, either.

I think the 4mm is about the smallest that would be practical at that length.

I'm going to be able to build a very aerodynamic electric car chassis from scratch for about $4K, even with $500 of bits... one step at a time.

 

Well, I need to make do with the 2.25" long up-spiral bits I have -- the company I wanted to make the longer bits cannot get 4mm carbide stock long enough to make them.

Oh well, I'll chuck up the sharp one I have and see ho the next sheet goes...

 

Why not use 1'' foam ? Instead of doubleing your drawings, just make 2 copies of the ones you have. Glue the copies together, same cutting time, same sanding time, but much higher percentage of good cuts. And I meant actual drill bits, like you buy at the hardware store, they may not be the best cutters, but with the right feed and speed???? The smallest in my little disaster area of a shop is 3/16, and
won't fit in the spindle that came with the flex shaft.

I still think you should just use 1'' foam. Stop fighting the foam and get on with this great project.

 

I'll look and see whether 1" thick 2'x8' sheets are available. That is a very interesting thought... The feed rate could likely get bumped up to 50ipm or something like that, or higher? The other advantage of this might be that any errors would be averaged.

I like it!

The RotoZip up-spiral 4mm bits I have cost "only" $15-16 each, at Lowes. The up-spiral pulls more dust up toward the vacuum orifice, and cutting all the way through, and then lifting up periodically for tabs will help cool the bit, since air come up through the open kerf and the Z motion spins the bit in free air.

I *really* like it!

 

I know that Home Depot has the 1" foam. I have four sheet in my shop, the pink stuff. Well... it's rated 1" but it is a little thinner. I don't know if the blue 2" is exactly 2".

 

The Dow (light blue) 2" EPS that I've been getting at Lowes is actually ~1 15/16" thick, so I'm guessing it is actually 50mm thick. If the Owens Corning (pink) foam is actually 25mm, or if the blue foam is 25mm, then I'm okay to use it. But if the two layers is significantly different than the way I've sectioned the SketchUp model, then I can't do it without redoing the sections.

Edit: the blue 1" foam is in 4'x8' sheets. The pink 1" foam is 2'x8' and is T&G -- I'd prefer square edged...

 

What about splitting the "stock" blue sheet in half with a hot wire? You could either use a vertical wire to split a 4' sheet (or stack of sheets" down to 2' or a horizontal wire to slice the 2" thick into 1" (minus the wire kerf, of course)

 

I could cut them in half with a straight edge and a sharp knife -- the foam will "snap" cleanly if it is cut most of the way through. That will be the way to go, I think.