My T-slot System

Discussion about Tooling and Fixtures. End Mills, Router Bits, Hold Downs, Fixtures, Etc.
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John_TX
Posts: 34
Joined: Tue Dec 01, 2015 5:17 pm

My T-slot System

Post by John_TX » Mon Feb 15, 2016 3:53 pm

I wanted a T-slot holddown system for my SO3, and chose http://www.mcmaster.com/#1850A14. I couldn’t mill ½” deep slots in ½” thick wasteboard, and I didn’t want to replace the wasteboard. Also I can’t use the SO to (easily) mill a slot longer than the SO work area. I chose a method that I think is easier.

First I cut the T-tracks to 22.8” (length of bed). Then I cut 3 strips from ¾ oak plywood 6”x18”.
(Just because I had a big 18” wide piece of ¾ oak ply – I’d have used 5/8 or ¾ MDF if I had it, but now that it’s done I rather like the plywood anyway.)

Then I screwed the 4 T-tracks down to the stock wasteboard with exactly 6” between them and laid in the plywood strips.
SO3.jpg
Before bolted or surfaced
SO3.jpg (120.76 KiB) Viewed 2171 times
I needed to secure the strips so they couldn’t move in the Y-direction so I countersunk some ¼-20 bolts and screwed them into threaded inserts that I installed in the stock wasteboard.
Then I surfaced the available work area. I was impressed by how well plywood handled this.
SO2.jpg
Surfaced
SO2.jpg (131.88 KiB) Viewed 2171 times
¾ stock leaves plenty of room to surface again and again if needed.
SO1.jpg
Clearance above track
SO1.jpg (125.21 KiB) Viewed 2171 times
However, I will still need to surface the portion that is outside of SO work area so that a large workpiece can lay flat. That was going to be a problem no matter how I did this – and it’s another reason for doing this with removable wasteboard sections instead of a whole new wasteboard.I can easily uninstall the ply boards, move them to the center of the work area, surface the extremities, then put them back. Also if my holes are located properly, I can switch any of the 3 boards into any of the 3 locations – maybe even rotate them 180 degrees.

Cutting parameters: Surfacing entire work area, oak plywood, using ¼” flat mill, 85 IPM, Dewalt611 at speed 4, stepover 0.2”. Single pass, 0.080” depth (was not so deep in all areas obviously – hence surfacing). I had no issues with these parameters.
Lesson learned: If I had thought with my head instead of my hands, I would have modeled the whole thing in AutoCAD, then printed 1:1 (D size?) and centerpunched every hole FIRST.

Now I need a dust shoe...

xfredericox
Posts: 292
Joined: Mon May 04, 2015 10:46 am

Re: My T-slot System

Post by xfredericox » Sat May 07, 2016 9:04 am

I've been thinking about the same thing (resurfacing outside the machines reach), but i've decided it isn't really necessary to have sacrificial board altogether in those areas. I just make the sacrificial board 1cm smaller than X and Y travel. This way I can always surface it 100%, and when my stock overlaps a bit, it will simply hang there, which is no biggie since I will never actually cut there.
Visit my blog for updates on my current SO2/lasercutting/... projects.
http://www.manmademayhem.com

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