Adding "Tabs" with the shopbot

[sagreen83]

Last night I cut out a piece of MDF, and told the shopbot to cut the tabs at a default height. I believe that was .1"

This seemed very high to me, but it was my first attempt. So, question, what heights is everyone using for tabs with various types of materials. And when you use the tabs, how are you cutting the part out of the tabs?

Thanx,
Scott...

[scott_smith]

I cut almost all MDF. I don’t use tabs to often but when I do I’ve used .1 and .05 they both work well. As for trimming the tabs off, use a trim router it works great.

[paco]

How long the tab do you suggest Scott with .1 and .05?

[scott_smith]

Size .5 or .6, leads .1
Keep in mind that cutter diameter effects the shape of the tab. I think I was using a 3/8" bit.

[paco]

Thanks! I'll test thoses values!

[sagreen83]

Scott,

I used the tabs again last night, and didnt see your message until after I cut out a full MDF sheet of parts with the default settings of the tabs. What distance between tabs do you use?

I am using a bit size of 1/4". I assume when you are talking about a "trim router" you are talking about one of the small hand held laminate trim routers. Do they make a bit with a bearing on it small enough to fit in a 1/4" slot?

Thanx,
Scott...

[fleinbach]

Scott,

Yes, they do make a 1/4 bit with a 1/4" bearing. It's usualy call a laminate trim bit. You can pick one up almost any place that sells router bits. They are primalraly used to trim the edge of counter top laminates.

The number of tabs can vary. With my old Prt96 I made all tabs 1/8 wide by 1/8 thick. The number of tabs was dependant upon how large and what shape the piece was. Small parts I'd say under 16" I would just use 2 tabs. Some larger parts recieved up to 4. This worked very well when cutting 3/4 MDF in 3 passes at 2.8 inch/sec I would usualy put 2 screws in a scrap area making sure there where tabs holding any pieces adjacent to the scrap piece.

I will be changing my method now that I have an Alphaprt 120. While cutting at 9 in/sec in one pass with an up spiral bit there was enough power that the bits up cutting action lifted the sheet off the table even breaking the tabs. It was suggested by Ted that I switch to a down spiral and I will be picking some up tomorrow.

[sagreen83]

Frank,

I have used 1/4" laminate bits as you mention to cut countertop. I was actually wondering if there is a smaller one, like 1/8" for one of these hand held trim routers. My thought was that if you used a 1/4" bit to cut with, and trimmed the the tabs from the sheet with a 1/4" bit, it would bind in the slot that was cut.

Maybe I'm asking the question wrong. Are you guys cutting or busting the part out of the waste, then taking the part to a router table to cut the tabs off, or using the trim router to cut the piece from the waste, and trim the tabs all in one process. If so, are you flipping the whole thing over on the shopbot table and triming from the bottom?

Scott...

[fleinbach]

Scott

I usualy just pick the parts up right from the table breaking the tabs as they are removed.They seem to always break right in half leaving only a small nubb. Then I trim them with a razor knife cutting down so as not to chip the piece. With practice you can make a pretty close clean cut. If one should break into the edge of the mateial I simply fix it with Redi-Patch while I am filling all nail or screw holes. This has always worked for me.