in the photos printed side is not shown.. this is DOW protection board from Lowes - it only has plastic and printing on one side (Unlike the DOW Blucore that Has plastic on both sides). I have not removed any covering just yet.

thanks for the video tip.

 

if it has plastic on both sides the writing is simple to remove, just go to a dollar store and get some stuff called "Totally Awesome" carpet cleaner. spritz it on the lettering and it wipes right off.

If it is printed on the side with no plastic your pretty well out of luck although i have heard some people use a sanding sponge to get most of it off.

 

I have been too busy cutting foam and making planes -Its working! but did want to share that the HF flex shaft is working fine. I did have to narrow down my v block mount to get my full Y axis travel.

The flex shaft cable has a quick connect coupling feature that I did not expect. It makes taking the motor off a breeze. I am supporting the motor horizontally behind the back opening of the PP. At the moment I have propped my PP up onto legs to allow a gentle radius of the flex shaft.

I also added a dimmer to turn on/off the spindle motor and to adjust the spindle speed if needed. I wired one outlet for the dimmer the other is power for the driver boards and electronics (not dimmed).

I will likely (later) rearrange the locations of my power supply and this dimmer box. So that the motor control would be more easily accessible. I also plan to look for a suitable relay to have the USB CNC board control my motor switching eventually.

changing bits is fairly easy - however MAKE SURE you leave your top cover free so that you can lift it off and make tool changes. I would not want to have to do this from the bottom!

I have run quite a few sheets of foam in the last week and the PP is performing perfectly. Today I even cut my first plywood parts - I was very surprised that they came out successfully being my first attempt at it. Plywood cuts were with the Dremel 1/16" bit. Now I will be sending away for a 1/16" fish tail chip breaker to do more.
Attached files

 

Shaun - Yes your plane plans are awesome! Thank You!


Now that I have everything working and an idea on how to cut plywood.. I am going to get working on my Y axis belt mod parts...

Report / for any future MK1 builders:
I have started with all my motors set for 20 IPM. I wanted to start slow and see everything work and allow some time for the rod and bronze bushings to break in. I just stepped up to 25 IPM yesterday.

I have my CNC USB settings like this (driver boards are set for half steps):

pay attention to the adjustable slider on the bottom of the lower left on the above menu page, this will detirmine how slow or fast your motors operate. if you get you the Y or Z axis stuck all the way at either end of its travel. slide this setting down very low. single digits and reverse the direction - very low IPM will give you maximum motor torque. Remember high IPM speed comes at the expense of motor torque. So lowering your IPM temporarily with this slider will help get unstuck.

For my set up, I checked the invert pulse boxes - based on the info from the Probotix driver board documentation.

My steps per unit were arrived at using the dial indicator (to mark start position and return to home) and the CNC USB calibration routine. I used my full travel for each axis to calibrate and this has been working great. I suppose I should revist these settings and see if using the backlash function is somehow better. So far its working better than expected considering I am still learning..

it took a few tries but I have a grasp on the bookmarking feature - it is helpful if you need to stop and start from a particular spot in the gcode.

I am still trying to get my soft limits to work at all..

I am off to read up on the backlash function.
viewtopic.php?f=264&t=2525&p=26215&hilit=fence#p26215 Attached files

 

Build update.. after getting a little time under my belt cutting foam I am looking to mount the foam support tables. First thing I tried was magnets. They worked quite well and were nice to remove but once I tried to cut the light plywood I came back to thinking about having the option to mount a fence of some kind. I did recall seeing several previous mods and I came across an unused section of T-Slot that I already had in the shop. Going to give this some design thoughts


NOTE to Probotix power supply users - check the position of the input voltage switch, mine shipped set to 220V. It will work set up this way, but It may be unstable under load. Move the switch to 115v if you are running off regular 110V outlet. Little red slider in photo below


Another Build note. IF you plan to do the belt mod... don't mount anything on either cabinet side where the Y axis is.... I will have to relocate some of my electronics eventually. Attached files

 

yes - Magnets work nicely and when I remove them they store up and out of the way - stuck to the side of my furnace cold air return register. My first attempt was to just use the flat head screws ( I used to secure the Alu angle to the MDF) on the PP to attach the magnets to. Worked OK but mounting a second magnet into the MDF really gives a positive hold. I used litte button sized magnets from Michaels, they are very strong.

I since modded my outfeed tables and now they slide into the T-tracks quickly and easily.

Here is my first attempt to build the roller for my Y axis belt mod. This was mostly stuff that was laying around and could be easily duplicated.. I had already ordered the pulley and Belt from McMaster Carr when bought my 1/2" rod and bronze bushings. I figure the next piece i need to make is a bracket to connect the loose ends of the belt to my gantry.. The cost from McMaster was excessive.



I still have not decided if I want to try to cut 1/4" MDF to make the stepper mount or just order a bracket. This bracket from interinar for $13 looks about perfect and the price is right.
http://www.interinar.com/mbpr-23ra-moun ... acket.html

UPDATE - bracket ordered.. will report on how it works out. Part arrived and looks like it will work nicely.

After doing a bit more reading up on older posts - I found a very good bit of info here in this post http://www.phlatforum.com/viewtopic.php ... 132#p31132

I will go with direct belt drive to get started.. but I may want to take advantage of gearing to get the most out of my existing motors. Attached files

 

Spent some time to get the belt mod in place.. and WOW - it hauls (200+). I still need to calibrate and dial this in. I will plan to change my driver board to 8th or 16th microstepping to get back some resolution lost due to the belt drive.

I built my idler pulley to be mounted on the outside of the cabinet (loading cabinet panel where the rib brace adds strength. The Idler pulley uses the cut off scrap from the pressure roller for it's 1/4" shaft. The gear and 1/4" bushing from mcmaster, angle Alu from anywhere. The 1/4' ID busings are pressed into the Aluminum brackets.

I used 2 more sections of angle Alu 2.5" long to make the belt clamps and these will get bolted to each other and grab the Y Gantry back rib in between. I chose to locate the belt pull location on to the gantry close to center point between the 2 slide rods. 2 small flat Alu plates screw down to the brackets and clamp the belt in place. I did mill teeth into the hold downs to engage the belt teeth. this worked out nicely to allow me to adjust the height of the belt a bit to keep it centered in the middle of the drive gear and idler pulley.

I can also adjust belt tension with the plates.

I thought I was going to have to mount my stepper outside the cabinet. Once the bracket arrived and I could play with it I found I was able to flip it upside down and fit the stepper back into the cabinet space

and the bracket mounted on the outside to take forces across the end panel.

This is actually the inside of the outer cover panel. The motor slides back into the original pocket for the Y axis motor mounted upsidedown. This works well as the belt tension is holding both the motor bracket and the idler pulley bracket against the outside panels.

A small notch was needed to fit the mount bracket into the original opening. seeing how well this worked I could concieve simpler ways to accomplish this MOD. One could tweek the kit to include the option to mount the stepper in either orientation.

This all worked out well and I did not have to remove any significant amount of the original stepper mounting structure. If needed I can put threaded rod drive back in. I did have to drill some holes for the belt to pass through (center slot not needed). I have retained the full 22" range of Y axis movement.

the motor shaft slides thru the slot already on the cabinet panel. The drive gear then needs to get mounted from a large hole that I drilled from the bottom of the original Y axis stepper compartment. The only disadvantage here is that if i locktite the gear to the shaft getting it back off if disassembly is needed will be a chore. If I were to do this again I would modify the side opening to accept the motor with the pulley already mounted rather than as shown. Applying a bit of locktite to the motor shaft under the belt drive pulley will really lock the drive gear in place.

In the image above you see the drilled hole for installing the pulley to the motor shaft after the motor is inside the motor pocket.
view of the completed idler pully mounted to cabinet

inside view of idler pully side.

view of the motor bracket mounted outside the cabinet


After changing my Y axis driver board to 8th steps and recalibrating for the changes. To start I ran my first test cut at 60IPM. It came out perfectly. I will have to see if accuracy suffers at all with the belt. There certainly is more potential backlash with the belt flex /strech. So i did dial in .006 of backlash for this axis. I have not been using any backlash compensation prior to now.

FYI - If I were to do it all over get these parts @ Hubbard CNC on Ebay. A solid Aluminum pulley $8 "CNC SERVO or STEPPER MOTOR DRIVE PULLEY 15T 1/4B AL" and the matching 0.20 pitch XL drive belt for ~2.50 a foot I used 5ft. If you were going to mount the stepper motor on the outside of the cabinet I think you would need a bit more belt.

I used the info here to calculate my steps per unit, since changing to the belt requires new settings.
http://www.probotix.com/stepper_motor_calculations/

Working on adding limit switches while I have things apart....
Attached files itle="IPhone 025.jpg" style="max-width:300px" />