Larger router bit use. P

[Artiglio]

Good evening all.

I’m looking to increase the size of an existing barrel channel in a rifle stock, currently it’s 34mm and i want to increase it to 38mm, i’ve bought a core box cutter to do so. However i’ve never used a cutter that large that’s going to be cutting on two sides at the same time. The stock is built from a dense ply type laminate which will cut and finish well.
Building a suitable jig to hold it and guide the router is no problem. Assuming i take light cuts of around 1mm at a time , is this likely to be problematic?
I do know someone with a suitable milling machine i can use , but with travel etc it’ll take me a full day, plus have to wait until it’s going to be available for me to use.
Cheers phil

 

[Trevanion]

That shouldn't be an issue if you've got a good jig that supports the work and router well. If you can reduce the RPM of the router to around 18,000 or so, that will help to limit friction and burning.

 

[Artiglio]

Thank you

 

[meccarroll]

This might sound wrong to some but as Trevanion has said only run the router bit at the recommended speed if it get hot or you see smoke the speed (RPM) is too fast and not allowing the cutter time to cut hence rubbing and burning rather than cutting.

Also don't linger in the wood most people feed a router too slow through wood and end up getting dust instead of chips from the cutter which works as an abrasive so burns and heats up the cutter. What you should be looking to do is remove chips of wood not create abrasive dust.

I'd probily start off with around 18000 RPM too maybe a bit less (Most cutters will come with a recommended RPM so use that), 3mm cut depth and push a couple of feel along the cut in two or three seconds or faster and see how that works.

Do a test run and see if it works for you, it's always best to do a bit of a trial run to find what works best for you and your equipment.

 

[Artiglio]

Again thank you, the cutter is from Wealdon and as you both mention has a suggested maximum of 16000 rpm. I don’t have any similar laminate to do a test cut on but do have some sapele offcuts of similar weight/ density. I’ll build the jig then have some practice runs with the sapele cut to fit the jig. Thank you

 

[Eric the Viking]

Couple of thoughts: Wealden cutters are excellent, in my limited experience, and seem now also to be quite good value - just this week I've bought a sash ovolo cutter and two panel raising cutters (with bearing sets) for around twice the price of a single panel raiser from Axminster, and the two Wealden cutters seem better designed than my old Axminster panel raiser, which they are replacing.

Your task in hand: I'd do it on the router table (so presumably holding the gun stock inverted), and use mechanical stops (I like 6mm or 8mm, long coach bolts, with locknuts) to ensure as much as possible I could only machine away what I was intending to!

I've now got one of those clever Incra fences that has micro-adjustable stops, so the bolts are no longer necessary. Widening grooves the way you've chosen to do it, especially in something that expensive, makes me a little nervous - you particularly need to ensure the stock can't move laterally at all during the cut, else you've wrecked it. The advantage of a slightly smaller cutter would be that, although you'll need two passes to keep it symmetrical, you only need to concentrate on one side at a time, and neither side needs to be a climb cut, so it's more controllable.

I had to do something similar recently, extending an adjustment slot on a camera mounting plate. That was in some sort of plastic-ish MDF, with a through slot of around 1/4" and a centred rebate above it of 1/2" - I needed the whole thing to be about 3/4" longer. I basically did what you're doing but with smaller cutters (and square ended, not the 'bullnose' style of the core box cutters).

I was caught out by the propensity to grab, even though the cutters were barely touching the sides of the original slot. So, if you can mock up a trial piece you'll find out what to expect, and forewarned is fore armed. I wouldn't attempt to do it moving the router instead of the workpiece - much higher risk of it going pear shaped (possibly literally).