I’m fairly new to woodworking, so please be kind! I have tried to read as much as I can on this and have followed on the tips I have read, but I’ve been struggling with burning up my router bits. I am currently using some leigh dovetail router bits. My last one I was able to make 7 drawers out of Baltic birch ply before it was black and toast. I am currently using a Bosch 1617EVSPK router. I have the speed set to 5.5. I let the bit do the work, I don’t force it through. I take a little less than ¼” with each pass. I know that plywood is harder on bits, but I’m sure you are supposed to get more than 7 drawers with a $30 bit.. I do get 2-3 times longer out a freud bits, but I don’t know if that helps tell you what I am doing wrong. The only other thing I can think of is maybe don’t do more than 1 drawer back to back so the bit has more time to cool?
Any advice here would be very greatly appreciated.
Replies
Have you tried cleaning the bit?
Never had any luck with dovetailing plywood of any type so I only use solid wood. Always destroys router bits of any make. Just my preference!
I have tried cleaning the bit every other drawer, which did help some. It did cut a little faster after each cleaning. I did not try cleaning it this last time, but as you can see from the picture I am pretty sure it's gone.
OK, that's ugly. I would guess that more frequent and thorough cleaning might help prolong the life of the bits. For deep cleaning I soak bits in undiluted Simple Green and scrub with a brass wire brush until ALL of the crud is gone, finish up with some WD-40. But I have to admit I've never tried using a router on plywood...
I wonder if you are taking too deep a bite and running the router too slowly, both in rotation and movement.
This bit looks to have been badly overheated.
I'd run it at the highest speed you can (it's not a big bit) and be very gentle, taking many quick light strokes to get to the full depth.
Th jig will not allow you to cut too deep.
Don't be afraid to take breaks - the bit is tiny and will not take much time to heat up.
Cleaning the cutters will reduce heating.
You can also try running the flat of the cutter on a diamond stone a few strokes to put a new edge on it. Success is variable in my experience.
I have a Leigh jig and bits but have never used on plywood. I haven't had problems with burning with those bits. Is it the adhesive in the plywood perhaps that is causing all the burning?
Thank you so much for all the tips! The bit was getting very warm, so I would slow down the router speed. Perhaps that was adding to the problem instead of helping.
I ordered a new bit and when it gets here I will try running it at a faster speed, taking smaller passes, and cleaning it more. I know plywood is harder on it, but it is what I can afford right now and I really like to practice.
When the new bit gets here next week I will update this so if anyone else has a similar problem maybe this will help, or save them a bit!
I think that you'll realize it eventually, but you can't really make light passes with a dovetail bit, it won't make a clean dovetail that way because of the shape of the bit. Speeding up the bit and slower feed rate might help, along with frequent cleaning. I think that the glue in the plywood melts when heated and clogs the bit, causing even more overheating.
I've found that clearing out most of the waste with a straight bit makes the dovetail cuts easier and cleaner.
I assume you are using carbide bits, high speed bits in plywood are pretty well useless, go easy at a high speed backing the bit off frequently and clean often
What Rob said!
I would try slowing down to a speed setting of 4(ish) as well. I’ve found that is the optimal speed for most of my router work.
To clean the bit completely use full strength spray oven cleaner to get all the resin off the bit. Let it soak a few minutes and wash or wipe off. The resin that builds up on the cutters can really effect the quality of the cut and heat generated. I suggest using a fairly high speed on the router and feed the bit a little slower through the work.
The glue in plywood is abrasive, stop using it.
The wood itself is abrasive . . .
Apparently the term abrasive is a confusing concept... My apologies...
I pre-plow the dovetail with a 1/4 inch straight bit to remove most of the waste. It really helps. Also, plywood was not meant to be dovetailed. There are other joints that work.
If you can clean out most of the waste on the table saw and then try clearing out the rest with the router bit .hope this helps cheers
It's the plywood. I bet if you dovetailed into cherry or walnut with the same bits and setup, they wouldn't burn.
zombie thread
Arise long dead thread and do my bidding . . .
Plywood is a rather harsh mistress. It'll ruin a set of planer blades pretty darn quick (ask me how I know).
Dovetail router bits generate a lot of friction/heat that melts the glue, which gets stuck to the bit.
Also, half of the plies that are being cut are end grain, which is notoriously tough to cut with a router. Just a second spent "in neutral" while routing end grain, and bada boog, the wood is scorched. One needs to move fast when routing end grain.
With a table saw, it isn't so bad because the wood each 'unit' of wood spends much less time in contact with the blade. Also, it is much easier for the heat to dissipate.
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