New 3/4" MDF Spoilboard for my 7x12

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New 3/4" MDF Spoilboard for my 7x12

Postby jblakey » Wed Feb 25, 2015 9:07 am

Hey Guys,

just finished (almost) my new spoilboard for my 7x12, and I thought i'd share. I'll post up the parts / gcode so if anyone wants to cut/build one, they can.


Parts
-------
3/4" MDF sheet, 17" x 8" (19mm thick)
20 T-Nuts, I used 1/4-20 x 9/16 (Got mine at Lowes, but Home Depot sells these too. Height is not critical.
1/8" endmill, with at least 1" cut depth. I used a 2 flute one that works well on wood.
10 No. 4 x 1" Socket Head Sheet Metal Screws (Du-bro). I like the socket head screws. Hobby stores sell these (Great Hobbies in Canada)
10 M3 Washers (Hobby store again, hard to find these tiny washers)
hammer for setting t-nuts
a pair of bolt/screws for screwing down MDF to old spoilboard

Procedure
--------------

1. Bolt/attach the MDF to your old spoilboard. I lined the front of the MDF up with the front of the old spoilboard, just to keep things neat.
2. Mark the MDF so you know where the middle is. Touch off to the middle of the new spoilboard, Z should be touched off to the TOP of the MDF.
3. Run the cutfile for the bottom of the spoilboard.
4. Remove the spoilboard, apply epoxy to countersink area, insert t-nuts, and hammer the t-nuts in place. I did 5 at a time so the epoxy didn't harden in the middle of the job. Make sure they sit flush with the MDF.
5. Reattach the MDF to the old spoilboard, but with the uncut face up (T-Nuts down).
6. Touch off to the middle of the spoilboard again, Z touchoff at the top of the MDF
7. Run the cutfile for the top of the spoilboard.


Remove new spoilboard, remove old spoilboard, screw down new spoilboard using 1" screws + washers instead of 3/4" screws. I used M3 washers for the new screws.

Taa-dahh!

I'll tweak the cut file for the top a bit (to do peck drilling on the through holes), but other than that, they're good to go.

NOTE: Most of the t-nut screw-down holes have no issues, but the ones farthest from the center on the X axis MIGHT run into the side of the machine from underneath if you use bolts that are too long. None of the other t-nut clamp holes have this issue. Don't use bolts that extend past the bottom of the spoilboard on these clamp holes!


I'll post up the G-Code tomorrow.


Thanks,
jason


Design Notes:

TOP (attach to CNC holes): The holes are 100mm apart on the Y axis, and 80mm apart on the X axis. The countersink is 6mm deep, and 8mm wide. Through hole is 1/8" wide.

BOTTOM (clamp stuff down holes): The holes are 90mm apart on the X axis, and 30mm apart on the Y axis. The countersink is 2mm deep, and XXmm wide (I forget right now, I'll have to check). Through hole is XXmm wide (Have to check this too).
Attachments
IMG_4292.JPG
IMG_4291.JPG
IMG_4288.JPG
Last edited by jblakey on Wed Feb 25, 2015 10:23 am, edited 4 times in total.
User avatar
jblakey
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Posts: 181
Joined: Fri Jul 29, 2011 11:18 am
Location: Ottawa, Ontario, Canada
Zen Model: Zen 0712 (Ext. Mod)

Re: New 3/4" MDF Spoilboard for my 7x12

Postby jblakey » Wed Feb 25, 2015 9:08 am

Some more pics...

Thanks,
jason
Attachments
IMG_4315.JPG
IMG_4313.JPG
IMG_4296.JPG
User avatar
jblakey
CNC Addict
 
Posts: 181
Joined: Fri Jul 29, 2011 11:18 am
Location: Ottawa, Ontario, Canada
Zen Model: Zen 0712 (Ext. Mod)

Re: New 3/4" MDF Spoilboard for my 7x12

Postby jblakey » Wed Feb 25, 2015 9:09 am

And a couple more pics... (3 max per post is a little limiting).


Thanks,
jason
Attachments
IMG_4315.JPG
IMG_4321.JPG
IMG_4316.JPG
User avatar
jblakey
CNC Addict
 
Posts: 181
Joined: Fri Jul 29, 2011 11:18 am
Location: Ottawa, Ontario, Canada
Zen Model: Zen 0712 (Ext. Mod)

Re: New 3/4" MDF Spoilboard for my 7x12

Postby jblakey » Fri Feb 27, 2015 8:52 am

Actually, I'm already working on version 2 of this project now...

stay tuned:)

Thanks,
jason
User avatar
jblakey
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Posts: 181
Joined: Fri Jul 29, 2011 11:18 am
Location: Ottawa, Ontario, Canada
Zen Model: Zen 0712 (Ext. Mod)

Re: New 3/4" MDF Spoilboard for my 7x12

Postby jblakey » Mon Mar 02, 2015 8:11 am

So, version 3.0 is done, and I'm much happier with it. I've learned two things:

1. The spoilboard should be centered under your spindle, not your existing table! When you're bolting your new spoilboard down, make sure when the spindle center (X3.5, Y6.75 on my machine) is directly over the spoilboard center, if you want a nicely centered spoilboard.
2. Try to get that spoilboard leveled! It'll just make everything easier later. A couple of washers epoxied down over the right-most screw holes of my machine's frame made a big difference for me. I think I'm now < 1 mm off across the entire board. Good enough for anything other than circuit boards, really. YMMV.

I've made the recesses cut into the top of the board deeper, so you don't need to use 1" screws, the old screws now work fine. I'm still using the extra washers there, though (Du-Bro sells these tiny washers, they call them "Number 4"). I've also made the recess for the t-nuts 3mm deep instead of 2mm deep - easier to get them sunk flush with the bottom of the board. And I'm now using peck drilling for the 1/8" holes that the screws will go through, so there's less complaining from the endmill.

Other than that, not much to report. The new spoilboard has an extra inch in the Y direction, just to allow rough bolting down of stock, if I need to.

Files run fine on my LinuxCNC 2.5 system, 1/8" endmill, about 40 IPM, if I remember correctly.

I also ran a job to mill a 2mm deep 1 cm x 1 cm grid on my board starting from lowest left hand corner using a 1 mm endmill. I can post that up, if anyone wants it, but it's tuned to my machine's exact worksurface (7x13.5), so I don't know if it'll help anyone else.

Thanks,
jason
Attachments
spoilboard_V3.7z
(9.05 KiB) Downloaded 208 times
IMG_4358.JPG
User avatar
jblakey
CNC Addict
 
Posts: 181
Joined: Fri Jul 29, 2011 11:18 am
Location: Ottawa, Ontario, Canada
Zen Model: Zen 0712 (Ext. Mod)


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