I’ve read in an older post that someone used a Dremel T-slot cutter 199 (https://us.dremel.com/en_US/products/-/show-product/accessories/199-high-speed-cutter) to do something similar. It’s a high-speed bit that can handle the 30k RPM, but I’m still not sure how well it will work in my Shapeoko. I’m using Fusion 360 to create the G-code program.
Does anyone have experience using Dremel cutters in the Shapeoko? Does anyone have experience using T-slot cutters in the Shapeoko? Is there anything I should be aware of?
I’ll let others comment but I remember a great piece of advice from @LiamN I think: don’t ever pause the job while using a T-slot cutter. Because…automatic retraction will make for an interesting kind of crash
The standard advice for this type of cutter is to use a straight cutter to clear the deep part of the channel first so that the slot cutter has less trouble getting the chips out of the cut.
Toolpath simulation will be your friend here, along with really good extraction.
Thanks for the advice @LiamN. I’m not sure what you mean by “straight cutter to clear the deep part of the channel first”? The way I was thinking of doing it would be to use a straight cutter to cut away all the material from the stock, so I’ll end up with the shape you see in the screenshot and then cut off that shape using the T-slot cutter.
Looked at your picture properly now and yes, you’ve already cleared out and it’s not a slot, you’re using it as a slitting saw / undercut. There’s quite a few cutters available that are set up to do this from people like CMT if the Dremel isn’t up to the job
I’d suggest taking a series of passes in Fusion at, say 0.25mm per pass and either leaving 1mm or so of the material to finish off with a pull-saw
As you clear out the material in the undercut that frame is going to start vibrating a lot and may well flap about, catch on the tool and end up as shrapnel before you can say “erm, that doesn’t sound right”
Does the cut on the underside need to be final dimension and smooth?
It might be better to have somebody resaw the wood on a bandsaw, put it through a sander / planer and then tape & superglue a piece of the right thickness down.
I’ll give the dremel tool a try first to see if it works. They’re quite cheap cutters, but there might be a reason for that .
That sure isn’t a lot to take at a time. I’m not sure whether it would be best to leave 1mm along the whole line as you say or whether to create full-width tabs. What do you think will work best when it comes to stopping the piece of wood from vibrating? Sawing off the tabs or line with a Japanese saw, in the end, seems like a good idea though.
I’ve been thinking about this solution as well, but sawing off the piece with an undercut saw would be much easier in this case. So I’m gonna give that a try before I go on to other solutions.
The underside needs to be relatively smooth and dimensions need to be relatively accurate. It’s for an updated model of a jewelry box that I posted about earlier in this forum: Advice on my first real project (jewelry box made from wood) - #11 by holgersindbaek. This specific part is the frame that goes around the mirror. So the side that the undercutter will cut off, is the side that’s pressed up against the mirror.
Honestly I have no idea whether leaving a continuous perimeter or tabs would work better, I’d do a small test piece and try it out (or hopefully somebody who already knows might tell us ;- )
What you could consider is machining it with a mm or two of excess on the bottom side, flipping it upside down, putting it in an MDF jig (Shapeoko out a negative) and then surfacing the topside down to final dimension if the Z dimension and face need to be accurate?
My main concern is the remaining strength of the wood, especially in the cross-grain direction once it’s cut this thin.
This is one of those cases where there is probably a better, non-cnc, solution to the problem. What about making an MDF template and using a router with a template bit? You could glue up an approximate rectangle so as not to waste so much big stock.
If you want to / have to CNC, I’d say start with the wood at the correct thickness. You can cut the outside profile, add some clamps and cut the inside.
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