Router Cutters

[elmo]

Hi everyone
Can someone help me with a small problem.
i've been fitting my kitchen and using my router with a 12mm TCT cutter on the worktops. The edge on the cutter is starting to go, would it be possible to sharpen it myself (if so how) or would i have to have it done professionally, maybe there's a bit of kit I can get that will make it easy. I would appreciate any help

Elmo

 

[Barry Burgess]

If you spent a couple of quid on the cutter buy a better one and continue. If its a professional cutter get it sharpened else it could be a waste of money.
I bought some cheap cutters and in time binned them all and bought the better ones - I might be wrong but if you damage a worktop with a cheap cutter - its an expensive cutter isn't it??

 

[Chris Knight]

You can easily touch up TC edges with a diamond "card style" stone. Work each edge with the same number of strokes. You won't be able to remove any chipping doing this but you can certainly improve cutting performance.

Eventually you will have to bin the cutter. Bear in mind that getting it reground by a sharpening service will change its diameter/profile slightly.

 

[Newbie_Neil]

Hi Elmo

I have a diamond stone for sharpening the cutter. You will need to use it about every 3 or 4 joints.

If you are using a cheap cutter it won't last very long cutting worktops, as the material is so abrasive.

Cheers
Neil

EDIT I must have got distracted as Chris's post wasn't there when I started. :wink:

 

[Scrit]

Hi Elmo

The carbide must be very sharp to cut the thick laminate properly which is why many kitchen fitters use replaceable-tip carbide cutters and do only a couple of joints with each fresh edge - to avoid chip-out. Also if a cutter is reground the diameter changes which makes it useless with a mason's mitre template. BTW are you sure it's not a 12.7mm (1/2in) cutter as that's the size normallyiused with templates? Personally I doubt that a hand honing will give you the sharpness you need in this instance.

Scrit

 

[Ian Dalziel]

as scrit says the carbide has to be sharp to do laminates without chipping. also hand lapping with a dia stone is a bit of waste of time

I used to use replaceable tip cutters but eventually found them a pain if the screws locked and or one came out so i now get my cutters sharpened.

the sharpener regrinds them on the inner face so the outer dia is still the same...this is the same way the manufacturer does albeit it he uses cnc grinders with air bearings. but he does a very succesful job of mine and runs a very succesfull business out of it.

Ian

 

[Scrit]

The sharpener regrinds them on the inner face so the outer dia is still the same...this is the same way the manufacturer does albeit it he uses cnc grinders with air bearings. but he does a very succesful job of mine and runs a very succesfull business out of it.

Actually, Ian, every time you grind the diameter of the cutter is reduced slightly (because of the clearance angle on the tips) so every cutter which comes back from the grinder for our CNC router has to be recalibrated - each and every time it's ground. For example our spiral carbides start at 12.7mm diameter and are thrown away (or simply break in service) around the 8.5mm diameter mark. With conventional hand woodworking this reduction in diameter makes relatively little difference - with a mason's mitre joint the error is doubled for every grind and the joint produced quickly becomes innacurate. So you might get away with one regrind, but everyone I know doing kitchens either buys a new cutter for each kitchen (kitchen fitter's sets are three cutters) or uses disposable tips.

TC-RT cutters solve this undersize problem because they maintain a constant cutting diameter - I use them on chipboard all the time as inclusions (screws, stones, etc) in MFC and chipboard write off solid carbide spirals in an instant. I also reckon that they're sharper because the cutting edge is thinner - they will certainly run at higher feed speed on the CNC than brazed tip tooling. Never had a problem getting the screws off them, though (I use Titman TC-RT in the main, with some KWO). Who's TC-RTs were you using that suffered from this problem?

Scrit

 

[Ian Dalziel]

scrit,
I know when you grind the dia of cutters it reduces them but if you dont grind the dia it cant reduce.

I had this argument with the my sharpener. I argued that it reduces and i need to recalibrate but he said only if you remove from the dia. when he sharpens he does from the inside face out and therefore itr doesnt reduce.....scrit please give him a phone and tell him such he has only being doing it for 18 years and will only work with swiss machines which have air bearings.

Better still send a couple of your spiral cutters when they need touched up and youll see what i mean....

pm sent with details

Ian

 

[Steve Maskery]

Sorry Ian, but I'm with Scrit on this one. If you grind the face, the diameter is reduced because of the clearance angle. Not much, sure, but a little, and for CNC routing, it matters. I would not have thought it made that much difference for fitting kitchens though, but then I've never fitted a kitchen, so I'll bow to greater experience here.

Cheers
Steve

 

[Alf]

We need Dave and Sketch Up to run us up a quick diagram, 'cos I reckon they get reduced in diameter too. If the bevel of the cutting edge was the exact diameter of the cutter I think it'd be uneffected, but wouldn't it also then be unable to cut 'cos you wouldn't have a clearance angle? I think? Maybe? Well it sounded right in my head anyway...

Tsk, just re-read what Steve said and I think I'm just saying the same thing but the other way about. #-o

Cheers, Alf

 

[Ian Dalziel]

OK Guys,
I nipped down to see my sharpener guy to have it out with him and this is what he said.

If you grind along the inside of the flute (this is what he does) ie spiral cutters this does not affect the dia of the cutter. this is the same method used when manufacturing and you have to be set up good to be able to do this

to regrind ie using something like J and S 310 tool and cutter grinders on the outside ie the dia then yes you will a few thou every regrind but this is not what i was trying to say earlier.

I was going to try and draw but i havent used sketchup for a long time and would take too long to relearn.


Ian

 

[Chris Knight]

Ian,

Your sharpener guy is just plain wrong I am afraid. If there is any clearance angle - and there has to be for a tool to cut - and if it is sharpened in any manner whatsoever, a small amount of metal will be removed from the cutting edge - this inevitably reduces the diameter.

 

[Steve Maskery]

OK, this is what I think is happening. I may not have the geometry drawn perfectly (this is zero rake) but I think it illustrates the point. It's all to do with the clearance angle.

The top red area is the original cutting edge and the arc it describes (its cutting diameter) The lower red area is the same face after sharpening. It is thinner because material has been removed. As the surface moves back, so the diameter reduces, because of the clearance angle. As Alf and Chris say, if there was no clearance angle then the diameter would not change, but has to be a clearance angle, doesn't there?

Is it possible that we are both right? Does the spiral geometry alter the rules? Personally I don't think it does.

It wouldn't be the first time that a highly-paid professional engineer didn't know something pretty basic. I was once asked to write a macro to draw automatically the development of the intersection of two cylinders. "Like this" says the engineer, who proceeded to sketch it with a sharp point at the top. They had always drawn them like this, because they only used 8 points of the circle to structure their curves. The sheet metal was then cut out, and of course it didn't fit. It had never fit for years, but what went on in the workshop, with the fitters snipping and bashing it into shape had neer got back to the drawing office! All I got for my pains of pointing out TACTFULLY (yes I can, if forced ) that I couldn't do that because it wasn't the shape required was a roasting for criticising a customer.

Anyway back to this sharpening. What's wrong with my reasoning?
Cheers
Steve

 

[Chris Knight]

Steve,
You are correct. A spiral cutter or not - makes no difference.

 

[les chicken]

Steve

"With my engineering hat on" You are correct and the illustration is good.

If the cutter is just being "touched up" rather than be resharpened then the difference in diameter might be negligible for now.

Les

 

[Alf]

That's exactly what I had in mind, Steve, thanks. I can't see that a spiral cutter is any different; just the same edge twisted up the cutter, no? It's worrying me though, 'cos usually this kind of question is way over my head... 8-[

Cheers, Alf

 

[Scrit]

H*lls teeth! Go away to do some work and wars break out..... :wink: Seriously, though, that's exactly what I meant Steve, and thanks for taking the time to post the diagram. The problem when granding carbides after they've been used on something abrasive like chipboard is that the sharpener has to do more than just touch-up very often because the abrasive adhesives knock seven shades out of the carbide and dub over the edge for good measure. All woodworking cutters (especially spirals) have clearance. So the more you grind the smaller the diameter becomes.

Scrit