Hopefully I'll get my SmoothStepper board soon, so I can use my PP instead of diddling with modifications. Anyway, here are the latest mods I did, including pictures of the micro-switch to automatically turn off the Dremel when it's at (or below) HOME.

 

Cool!

Where did you order/get the High density plastic?

Eric

 

It was a leftover from a kitebuilding class, but TAP plastics and Port Plastics carry the stuff all the time. I'll see if I can find a direct link.
Here's one - http://www.usplastic.com/catalog/produc ... t_id=10369
and another - http://www.tapplastics.com/shop/product ... 1657560386
Most places want to sell a 48"X96" sheet, but nothing smaller.

 

Yep,

Yea my first machine was made from 3/4 HDPE.

Freaking great stuff.

Instead of t nuts for the althread I made some more ZBN's for the PP. You wouldnt beleive it unless you had it in your hand but there is no backlash and you can spin it like a top on the allthread (no binding). It's better IMO that backlash nuts. It doesnt wear against metal.

I have ran many machines with the HDPE nuts. I have never caught one with any slop/backlash.

It will be added to my mod list soon when I finish taking pics of the gantry.

Eric

:Correction Made sorry:

 

OOoooo! Great idea! I've got a few pieces of Delrin out in the garage, maybe I can figure out how to make a couple with my tools. Man, sometimes a small lathe would sure be handy! Maybe I can mention that to my wife - maybe a Taig.

 

IMHO the prob I have with backlash nuts is they are made from delrin and delrin even though it is inpregnated with glass, it wears and has to be adjusted and then replaced.

If you have at least some 1/4 or 3/8 HDPE left over I would consider using it in replacement of your T nuts. If you have some allthread left over, just drill out your hole in the HDPE, (have to look at the tap and drill bit chart for the drill bit size) grind your allthread at an angle a bit smaller than your drilled hole, run a nut down the allthread to clean up the threads and then take your rotory tool and cut a nice V in the allthread about 1-2inches up for the spirals to feed into. Basicly make a tape for your allthread...with your allthread.

It maybe a little tight after the first tap. If so, put the "tap" allthread in your drill on high speed and run it in and out a few times and check it (check it often) till you can get the piece of HDPE to free spin a few times when you flick it with your finger.

This is about the only way to get the HDPE nut's threads to loosen, it takes the high speed to do it. After that, it will stay right where you have it as the stepper motors can not spin fast enough to wear the threads more and you have a almost perfect for ever nut.

I do not suggest using a 1/4 tap for this. I have never got the perfect results from them as I have by making the allthread a tap. Either the threads make slop or its too tight due to the threads not matching the allthread or the thread cuts are too fat or too thin.

Like I said I have made many. The one I used for the PP has been used a billion times and it shows no signs of slop or backlash.

Lathes are nice to have when you need them but here you dont. Just a 2 or 2 1/2 inch by 3/4 or 1 inch peice of flat 1/4 or 3/8 piece of HDPE rectangle with a hole in it and two self tapping screws. I wouldnt go thinner than 1/4 thick HDPE. You kind-a need the 1/4 of threads.

Eric

 

Well poop! I was thinking of the Delrin 'cause I've already got that. But if it's not worth the bother, then I'll leave it alone.

 

What material is cutting boards made of? Any chance it is HDPE?

 

Yes, HDPE, High Density PolyEthylene

 

Well Dorsal I know being able to make some with something you already have laying around would be great but I do make them and have planned on putting them up on the site incase others wanted to use them as well.

Eric

 

So, I've finished some more mods - probably the last.
First, I fixed a problem I'd created when I added the microswitch to the Z-gantry. Specifically, if the Z is within 5/8" from the top, and the Y is within 3/4" of the far left end, something's gonna break (interference). I sanded 3/16" off the corner of the roller-support box to make room, and here's a couple photos.

Next, I addressed the wire clutter and added a wire-track, some Adelle clamps and some tie-wraps.

Now, let's get to the real change - I changed the Y-drive to a 3/8-12 Acme thread rod. I decided to use my delrin to make a flange-nut for now, I'll get the HDPE next time I'm near a plastics store. btw, All the new hardware was bought from HUBBARD-CNC-INC.



Well, I think that's it. I drug the PP into the house to run it from my desktop for a test.
At first blush, X is running at 300 / 20, Y is at 45 / 18 but it binds near both ends and Z is at 13.5 / 8 -

Oops, I forgot to re-do the calibration for Y. Be right back! :? Attached files yle="max-width:300px" />

 

Okay, I actually squirted some oil onto the rods, re-aligned the homemade flange nut for the Y-axis, re-calibrated the axes, and here's what I can get at the moment.

X is running at 1049.396 Steps, 75 Velocity, 20 Accel. (that's 125% of the Y values)
Y is running comfortably at 17185.781 Steps, 60 Velocity, 20 Accel.
Z is slowest at 31746.032 Steps, 17 Velocity, 15 Accel.
So, maybe I need to change the shaft on Z to Acme also.

By the way, from my "Running Mach3 from a Dell laptop" post, before these latest changes I was getting:
X= 1049.396 Steps, 45 Vel, 18.75 Accel
Y= 31901.106 Steps, 25 Vel, 15 Accel
Z= 31746.032 Steps, 25 Vel, 25 Accel.
So there are the numbers for comparison. I have no idea why Z is now less than it was, but the shaft does squeak every so often - maybe it's the cold, rainy weather.

 

Good deal Dorsal,

LIke I said before, the delrin nut is great but will wear.
If you happen to get an Enclosure from me down the road I'll throw in one of the Zero Backlash Nuts (ZBN's) I make, in the package for you.

Did you make a piece of the allthread as a tap for the delrin? If so you should not be seeing any slop whats so ever.

The track is cool in there man, did you make that one or buy one?

Eric

 

Thanks for the compliments everyone.
I used a piece of the same Acme rod to make a tap - I hand-sawed 4 flutes, used the Dremel to shape the cutting edges and provide chip relief, then tapered the first 1/4". I used a 1/4" pipe tap as a model. It cuts great!
I bought the wire track from Hubbard-CNC, along with the Acme shaft, Lovejoy couplers and a 10' piece of 18-4 wire to replace the wire for the Z-axis with a piece long enough to allow for the wire track routing. Some of you have leftover wire from your Bonez build, and that would have worked perfectly, but the Premium kit doesn't have any extra.

Since the 3/8" rod is 150% the diameter of the 1/4" rod, it is (150% cubed = ) 337.5 % or 3.375 times as stiff in bending (assuming the same cross-section). The shaft I got from Hubbard was very straight, but the added stiffness means the alignment of the motor/flange-nut/far-side hole become more than thrice as critical. Another way of saying this is the alignment tolerance is now 3.375 times smaller than it was with the 1/4" shaft. I accomplished the "final" alignment by slotting the screw holes that attach the nut to the gantry, then adjusting the nut along those slots before tightening the screws. The slots are only 1/16" longer than their width, but it created a world of difference.

 

If anyone is having trouble finding the parts I installed, the 3/8-12 acme rod is here: http://tinyurl.com/8rvmpf (under "Screw Drives") and it's $8.99 for 3 feet.
The wire track is here: http://tinyurl.com/9y8j9z - Buy the 3-foot long piece. Mine needed all but 8" of the track, so I left it intact, but it's pretty easy (if time-consuming)to disassemble the links. That, by the way, is how I got the Dremel cord inside the track, because the plug won't fit through and I didn't feel like disassembling my Dremel again to get the cord out.

 

Thanks for sharing. The Y stepper looks like the stock one. Is that right?

-Kwok

 

I haven't changed any steppers from the stock ones, and after I change the Z-rod to Acme threads, I don't think I'll need to. I should be able to run all 3 axes at 60 ipm or better! :ugeek:

 

Why cubed? I know squared (pi x r squared) but cubed?

Yoram

 

I do have another coupler like that for the Z-axis, but I was thinking I might try to ream out one of the flexible couplers I have to fit 3/8 on one end, instead. There just isn't much room to fit any kind of a stop onto the shaft for the Z-axis, so I'll either use the flex coupler (which doesn't come apart) or screw a brass plate to the top of the Z gantry as a stop for the shaft. Maybe I'll be allowed to get to that today.
("Yes Dear, but Christmas can wait, I've got work to do on my PP.")

 

That was before. I have now changed the Z-axis shaft from 1/4-28 to 3/8-12 Acme also. I also reamed one end of one of the flexible rubber couplers I had to fit the 3/8 shaft and it works well. This way, the shaft is restrained without the need for end-plates or shaft collars (like I did to the Y-Axis).
The settings at the moment (with only a couple minutes of run-in time, total) are:
X= 1049.396825 Steps, 75 Vel, 20 Accel
Y= 17185.78132 Steps, 60 Vel, 20 Accel
Z= 21256.37763 Steps, 40 Vel, 15 Accel.
I am running the stock Easy-CNC steppers, V-Ref is set at 1.20 - 1.21Volts and PFD is set to the minimum (fully CCW)for all 3 axes.
Summary: Save your money on the new Steppers and change the drive-shafts instead. And turn the voltage down. Then spend the difference for under-the-hood lights and blinged-out control-board enclosures.

 

Man, something else to buy. Got many questions for you. Was it hard getting the nuts out? My flange is facing up, too. Hows about a picture of the z-axis mod and a pic of you home made tap? How much acme thread would you recommend buying for the mod? I see they have a 6 foot length, also. I assume one 3 foot length, is not enough?

-Kwok