trimming 0.25mm off a surface with a bearing guided router c

[flanajb]

I have a master template that I need to spray, unfortunately, said master plug has already been used and has been sprayed with a silicone release agent. I have sanded the plug, but every time I spray it, the paint glazes. Fighting a losing battle!

The plug in question is a clock bezel. My next cunning plan was to get a bearing template router cutter and switch the bearing for one 0.5mm less in diameter to the cutter. That would enable me to make a slight under cut all the way around. Once I had done that, I could switch the bearings back and I would then be able to take off the 0.25mm all the way around the external face.

Trouble is. Bearings for cutters only seem to come in different sizes so am struggling to figure out a combination that works.

Anyone out there have an alternative plan that might save the day?

I did contemplate trying to sand it back to bare MDF, but when sanding a circle it is very easy to get low spots, and these will show up when the bezel is sprayed high gloss

 

[CHJ]

Lathe?

 

[paulrockliffe]

1/4" bearing would only be 0.35mm larger than a 6mm bearing, you might be able to do something with a 1.4" trim cutter?

 

[Myfordman]

I often put a layer or two of tape on the bearing for a fine cut increment.

 

[blackrodd]

I have a master template that I need to spray, unfortunately, said master plug has already been used and has been sprayed with a silicone release agent. I have sanded the plug, but every time I spray it, the paint glazes. Fighting a losing battle!

The plug in question is a clock bezel. My next cunning plan was to get a bearing template router cutter and switch the bearing for one 0.5mm less in diameter to the cutter. That would enable me to make a slight under cut all the way around. Once I had done that, I could switch the bearings back and I would then be able to take off the 0.25mm all the way around the external face.

Trouble is. Bearings for cutters only seem to come in different sizes so am struggling to figure out a combination that works.

Anyone out there have an alternative plan that might save the day?

I did contemplate trying to sand it back to bare MDF, but when sanding a circle it is very easy to get low spots, and these will show up when the bezel is sprayed high gloss

Silicone is one of the problems experienced by car body sprayers.
They use panel wipe, or similar to clean the silicone off, which is even found on human skin, i believe.
Regards Rodders

 

[flanajb]

1/4" bearing would only be 0.35mm larger than a 6mm bearing, you might be able to do something with a 1.4" trim cutter?

That would be ideal, but the usual issue is that if the bearing is metric, then the centre hole will also be metric and therefore will not fit the shaft of the imperial diameter cutter.

I might give Wealden Tools a buzz to see whether they might be able to help.

Edit : Just checked their web site and they do a 12mm diam bearing with a 3mm centre hole and a 1/2" bearing with a 3mm centre hole. So if they also sell a 1/2" cutter with a 3mm centre hole then it's game on.

 

[Phil Pascoe]

I often put a layer or two of tape on the bearing for a fine cut increment.

I dismissed this idea at first, as you need the bearing smaller, not larger - but thinking about it of course you could start with a bearing that is too small and find something to sleeve it til it was OK.

 

[ColeyS1]

I bought a cheap flush trimmer that has a replacement cutting tip. if you keep the cutter sticking slightly proud its ideal for a little timber tickling :lol: then flush trim after. think its called 'rotatip' or something. I've only ever used it for easing slightly undersized housings/holes

 

[flanajb]

Finally found a solution. Router cutter shanks and cutter diams are one place where metric and imperial are mixed. Axminster to a 1/4" shank internal diam bearing with an outer diam of 9.5mm.

Pop that on the shank of my 10mm cutter and I have a 0.25mm undercut trimmer.

Improvisation and thinking outside the norm are two reasons I love woodworking!