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Bearing-guided round-over and bevel bits for steel plate?

ballen

Diamond
Joined
Sep 25, 2011
Location
Garbsen, Germany
One of my go-to woodworking tools is a set of bearing-guided bits for doing small-radius roundovers and bevels on edges. I put them into a 2HP Bosch hand-held router or a smaller trim router and run them around the edges of parts. I have also used the woodworking bits with aluminium and brass, sprayed with a bit of WD40 as a lubricant and to prevent buildup on the cutting edges.

Does someone out there make a similar bit out of carbide or ceramic which can be used on mild-steel plate? For appearance I'd like to treat the edges of some steel plates. Sure I can do it on the mill but the setup will take 20 times as long as if I could use a hand-guided tool. I'd be happy with roughly 3mm (1/8") wide bevels or roundovers, so we are not talking about removing a lot of meat. (I have not tried this with a woodworking bit but am 99% sure that the carbide would fragment when run on steel. I think different material and/or relief angles are needed.)
 
I'm lost..are you implying you would use a typical hand router with a guided bit suitable for steel to slightly dress the edge of a steel plate..a hand held router that spins at 20K?

Stuart
 
you really need a carbide burr . the stationary chamfering machines use a cylindrical cutter with an angled base .
you could use a conical burr, and modify the routers' bases with a vertical fence , mount outboard roller guides to the
base instead of the cutter , or a combination of both .

VS routers can turn at 8k rpm , and most die grinders run 18-25k rpm.
 
I have used a carbide tree burr with a collar in my variable speed router on various occasions to dress plate steel from a shear. Just don't try it on a flame cut edge.
 
Thanks. I'm not looking for a machine, but rather for a bearing-guided bit with a 1/2" or 12mm shank that I can put into a hand-held woodworking router.


And I'm just pointing out the sort of tooling it takes to do the job.

This ain't a hobby shop for kids.
But you could check with harbor freight, they must have something.
 
I use the 4flt Freud wood bits with 1/2 shanks in a vmc, 12,000 rpm with the bearings removed all the time in aluminum. A few years back an employee forgot to remove some hardened steel hold downs for an aluminum part he was running, I was very supprised at how nice a radius it put on the hold down, he stopped the machine after it cut about an inch and a half, it broke a corner above the radius but all in all it survived. You might just try one, conventional cut with oil and see how long it lasts.
 
you really need a carbide burr .

Thanks, I just read about carbide burrs, that seems like a good solution. I can use a 90 degree countersink burr with a 1/4" or 6mm shank running in a router set to 10-15k rpm. Can I make a 3mm (1/8") wide bevel in mild steel in a single pass or will multiple passes be needed? Do you recommend single cut or double cut?

The only place this might not work is on some curved edges, where I really need a bearing-guided cutter. But most of the edges are straight.
 
Thanks, I just read about carbide burrs, that seems like a good solution. I can use a 90 degree countersink burr with a 1/4" or 6mm shank running in a router set to 10-15k rpm. Can I make a 3mm (1/8") wide bevel in mild steel in a single pass or will multiple passes be needed? Do you recommend single cut or double cut?

The only place this might not work is on some curved edges, where I really need a bearing-guided cutter. But most of the edges are straight.

I also use ball-bearing router bits as you describe, including with aluminum. I would say that a standard 2-flute chamfering tool MIGHT survive for a while cutting steel in a highly-controlled rigid spindle machine (as Kustomizer referenced), but in a hand-held router, I also think you'll lose the carbides fairly quickly. In my experience, on aluminum a rough and finish cut (climb-cut) are required for a "nice" finish, and aluminum has considerably more resistance to material removal than plastics or wood. I think a 3mm radius or bevel in steel would require several passes at lower RPM (= more effort to push through cut, more chance to break something) and none of those would be climb-cutting;-) Chances are it's not something I would enjoy doing.

Burrs are the tool of choice, from what I have seen in steel edge finishing. Whether anybody builds them with tracing bearings is an open question. In the choice of single or double cut, I would just look at whether a single helix direction is going to give trouble with feeding material. The double cut is likely more fragile in tooth config, but maybe more stable for hand work.
 
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For curved surfaces you could use a follower bearing attached to the router base, as in laminate trimmers.

I've cut aluminum and brass on a heavy woodworking shaper w/ lock edge hss knives. Kinda scary, the chips are like shrapnel, made myself a plywood apron! And I knew a guy who routed a groove in the cast iron top of a new Martin table saw to install a long flexible Starrett ruler. He just used a 2 flute carbide bit.
 
I did something similar recently. I had intact cemented some 18 ga mild steel to a 3/4” plywood base. Th steel hung over the edge of th plywood in a couple of places and I wanted to trim it up. I used a 1/2” 2 flute carbide bit. It did the job, was very scary and pretty much ruined the but. Good luck.


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