here is a sample the circles were cut out of 1/4" bb ply with a 1/8" downcut one pass. the other parts were cut out of 1/8" bb ply one pass a 1/16" downcut bit. This works well but it depends on the plywood/material the size of the bit number of passes. But seldom do I need tabs but it may slow cutting down. but you don't have to clean the tabs off or cut them either.
I've been looking around trying to find some tab cutting solutions. I'm working a vacuum system, but imagine I will still need to use tabs on occasion and would like to have a good method in place.
I was thinking back to my earlier woodworking days before I had any of those fancy flush trim bits with bearings. I would just use 1/4" or 1/2" straight bits and let the shaft above the cutting length be the bearing surface on the pattern. It got me by.
So why not just use 1/4" spiral cutter bits with a short cutting length (like 1/4") in a laminate trimming router to cut the tabs from the top on 1/2" or better material?
I don't know-Why Not?
Actually if I am going to use a router and did my object cutting on the bot with a 1/4" bit I don't like having to "shove" a 1/4" bit in a hand router in the slot.
Although I don't do tabs often, for wood, depending on the thickness and size/shape of the pieces, I may use a router, knife, razor, Japanese dovetail saw, or chisel.
I see your point about needing to undersize your tab cutting bit, compared to slot size.
I have been searching for a spiral 1/8" DIA bit with a 1/8" and a 1/4" cut length. I have found some with 1/4" cut length, but not 1/8". The thing I am concerned about is that the machining of the bit extends well past the cut length, which gives you less room for error on the finished surface.
Don't like to use tabs as well but sometimes still best for small parts, I cut it out with jig saw with fine blade or a vibrating multitool with a slim attachment for sturdier parts or a wood cutting disc on a Dremel for delicate ones. Or, I cut the tab so thin that I can break it out without tearing. I wish I had not sold my scroll saw since that might be the cleanest and least damaging way for small stuff.
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I use a 3/16 flush trim bit in my trim router.
I use a Rotozip to cut my tabs. Since I use a 1/8" sacrificial board under my material, I can set the Rotozip bit to cut just barely through and the tabs and skins cut very easily.
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I use a Harbor Freight oscillating tool (used to be called a "Fein Tool" before their patent ran out) with a Bosch 3/8" Wood/Metal blade to cut the tabs, then take it to the table router with a piloted trim bit to smooth them off.
A Dremel tool cutoff wheel works well for some items, you want to locate the tabs so they are easy to cut.
The decimal point seems to be the most important on the z axis... x & y not so much....
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