Jump to content

Entry for April 2020's Guitar Of The Month is open - ENTER HERE!

Archived

This topic is now archived and is closed to further replies.

SJE-Guitars

Router Fretboard Radiusing Bits - Anyone Interested?

Recommended Posts

Yep many thanks Steve, I am sure many hours will be shaved off a job with these cutters as this is probably one of the most important and tedious jobs to get right 100% of the time and these will produce some accurate repetitions every time well done on making my life alot easier "CHEERS!" Laz

Share this post


Link to post
Share on other sites

Ok - hang on -

I read more closely, and while tool steel is fine for the bit shaft, for the cutters I saw "carbide-coated blades" - to me, this does not mean "blades made of carbide".

I think to make this work for the woods folks often use for fingerboards - woods that are quite dense and very hard, and sometimes acrylicized - you need carbide blades if you want the bit to have any longevity. And that means diamond tooling in the shop that makes them.

What's the cost of one with geniune carbide cutters?

Share this post


Link to post
Share on other sites
Ok - hang on -

I read more closely, and while tool steel is fine for the bit shaft, for the cutters I saw "carbide-coated blades" - to me, this does not mean "blades made of carbide".

I think to make this work for the woods folks often use for fingerboards - woods that are quite dense and very hard, and sometimes acrylicized - you need carbide blades if you want the bit to have any longevity. And that means diamond tooling in the shop that makes them.

What's the cost of one with geniune carbide cutters?

Basically all the bits that Stumac sells are carbide tipped bits and your original bits were carbide tipped - that's what they make.

In terms of dense woods over here everything is made from dense woods thats is the only kind of timber there is here basically 800Kg CM3 and upwards. This shop make basically all bits that are used by nearly all timber processing companies here.

They do not make solid Carbide bits.

The simple answer is if don't think they'll do what you want then don't order anything but I have say I find this comment slightly bemusing when you paid $200 a piece for your original blades made exactly the same.

I've never tried to cover anything up in my post the very first thing I state is the "bits are tool steel with carbide coated blades".

Anyway I'll should have the blade later today so for those interested in a Tool Steel bit with Carbide tipped blades I'll hopefully post pictures later.

Share this post


Link to post
Share on other sites

Easy there SJE :D Erik wasn't acusing you of anything.

You said carbide coated, not carbide tipped. There's a difference.

If the cutting blades are Carbide, then they are similar to what stu mac sells. If they're just coated, then they aren't.

Can you clarify if this is just a question on semantics?

Share this post


Link to post
Share on other sites

Yes, Todd has it - to me "carbide coated" sounded like the blades themselves were made of tool steel like the rest of the bit, just "coated" with a layer of carbide instead of being made of carbide. If they are indeed carbide blades on a tool steel shaft, then yes that would be exactly what I have.

There are plenty of router bits that are made with steel cutters, and plenty with carbide cutters - I just wanted to verify which these were.

Share this post


Link to post
Share on other sites

My apologies - I understand what you are getting at now - was early in the morning before! :D

The language used here and the way it was said just meant they attached carbide to the bit - when I go collect it I'll check with them what exactly the procedure is - I would still think it's carbide tips but I'll double check.

Share this post


Link to post
Share on other sites

Yep - that's how the originals were made. The shaft has a shelf milled into it - the carbide blades were milled separately, then attached to the shaft and sharpened.

Share this post


Link to post
Share on other sites

Anyway it was ready 6pm tonight - however I didn't have time to go and collect it - I will get it in the morning (it's 7pm here now).

So tomorrow I will have some pictures and hopefully do a test. :D

Share this post


Link to post
Share on other sites

Well there has been a minor hitch . . . . a certain person (aka Me) when I did the CAD diagram for the bit put in diameter as 12" opposed to the Radius! :D

Even though I only did the diagram as an example for the shop and I actually showed him using a steel ruler that I wanted a 12" radius they then just followed the diagram and produced a perfect 6" radius bit! B)

Anyway the correct 12" diagram complete with correct radius sizing has been given to them this morning so it should be done for Monday! Bugger - a bloody stupid finger error in CAD - highly annoyed with myself when I realised what I'd done!

But anyway I can confirm that the blades are Carbide tips - not just coated tool steel as you'll can see below:

bit1.jpg

bit2.jpg

bit3.jpg

So anyone want a 6" radius!?!???! :D If only I had planned for a 15" - then I'd of at least got a useable 7 1/2"! B)

Share this post


Link to post
Share on other sites

Well even though it's only a 6" radius bit - I couldn't resist having a play! :D

So first off trued up a piece of stock I had lying around - this wood is actually Malabar Ironwood which is a seriously hard timber so the blade isn't getting an easy ride - neither do my jointer blades!

Trued and with as near a centre line I could get (75mm wide so 37.5mm ain't easy to mark when I only has a carpenters pencil at hand)

step1.jpg

I could tell that the line wasn't total central so I set the height of the bit to the tip of the cutting blade to 37.5 using trusty the steel ruler

step2.jpg

So I clamped on the table and ran the router across the two edges - it cut real easy - a bit to easy actually I had to pull the router back as it just wanted to run off. The cuts were actually done in one pass on either side - since this is a piece of spare stock I could do things a bit quicker than a slotted fretboard. The end result:

step3.jpg

A couple of close ups of the surface after the cut - as you can see they are pretty damn clean cuts!

step4.jpg

step5.jpg

Then for a bit of fun - comparison to a Stumac 10" radius block (tightest I have):

step6.jpg

Obviously the most important part is making sure the fretboard is absolutely true otherwise the radius will be off centre but other than that (and getting the right size bit made!!) it will make radiusing an absolute doddle!

Share this post


Link to post
Share on other sites

Steve the main thing is that it works and if it can cut hardwood like that then there is no problem with it cutting others. Its a bitch when you get it wrong and its your fault "been there done that" but at the end of the day it's an easy fix and not the end of the world. Looking forward to seeing the new bit when you get it. Laz

Share this post


Link to post
Share on other sites

Whoa whoa whoa....you're not using the bit in a router table?! It might just be me, but I wouldn't use a hand router with any bit capable of grabbing more than a small amount of wood :-D

A 6" radius might well do some more extreme Jazz bass style fingerboards, as they're the closest to 6" I can think of (9-1/2") :-D

FWIW, having say 1.0-1.5cm in the centre of the fretboard for the bearing to run on will leave enough of a "flat top" for radius sanding down to a good 12" so I wouldn't say the bit was unusable, although it would mean thicker blanks to begin with making it trash for economical production!

<EDIT>

Here's a diagram I through together of "semi-radiusing" an 8cm wide blank to 12" by offsetting the 6" bit by 1cm from the centreline, which leaves a 2cm flat spot on the top. There's very little extra work to finish sanding this radius through to 12" from thereonin. The bit will still be useful in this respect, perhaps.

sixtotwelve.jpg

Share this post


Link to post
Share on other sites
Whoa whoa whoa....you're not using the bit in a router table?! It might just be me, but I wouldn't use a hand router with any bit capable of grabbing more than a small amount of wood :-D

A 6" radius might well do some more extreme Jazz bass style fingerboards, as they're the closest to 6" I can think of (9-1/2") :-D

FWIW, having say 1.0-1.5cm in the centre of the fretboard for the bearing to run on will leave enough of a "flat top" for radius sanding down to a good 12" so I wouldn't say the bit was unusable, although it would mean thicker blanks to begin with making it trash for economical production!

Actually the bit is really easy control by hand and the narrower 12" upward will be even easier with even less of a gyroscopic effect. I have a 1" rollover bit for shaping now that is a hairy bit to use!

Anyway this was just a quick test which I couldn't be bothered to dust down my router table (don't really like them!)! Far easier just square up a chunky off cut and run the router over freehand. B)

When I get the 12" the unradiused edge of this wood will be the tester .. .. freehand again . . . :D

All I need to do now is make a 6" radius sanding block and Jazz basses here I come!! :D

Edit .. .. hmmm I guess the theory is the curve is twice that of a 12" so only radius half the space you'd end up with a near 12" - albeit with the flat middle .. . interesting!

Share this post


Link to post
Share on other sites

That's where a 12" block comes in handy - talking of which, I have to get cracking on radiusing this ebony board here to 12" since I didn't get around to it yesterday :D

Share this post


Link to post
Share on other sites

Looks like a nice thick piece of carbide. Cant say I like the green color reminds me of Grizzly tools, Ha. Wonder if that color is a trademark? Hopefully it's balanced as well as I can see lots of chatter marks on your test piece.

I would certainly use it in a router table and use a fence rather than the bearing. If you ride the bearing on the neck you will have a flat spot. Of course your sample uses a piece of lumber 5x's as thick as a fingerboard so seems like your test will be easier than true life. That again is why a router table will most likely be a requirement.

Share this post


Link to post
Share on other sites

Hehehe - rumor has it, from more than one vintage repair guy, that there are a few 50s-era Teles out there with 6" radius fretboards.

step5.jpg

Looks very good - you will notice from the photo that there is a bit of a flat spot in the middle of the board, that is exactly what I get on some of mine and I think it comes in part from (A.) the bearing being very slightly larger diameter than the cut diameter at the top of the bit; and (B.) the router, or the wood piece itself (or both), being slightly out of true 90° - it goes with the territory. It can be fixed by using a cut depth that is slightly greater than 1/2 the width of the board, the flat spot gets narrower and just a little sanding is required to blend it in with the rest of the radius. But if you go too far, then you get the bearing riding on the curved part of the board and this results in a deeper cut on one side of the board than the other. :D

I think the results would be even better in a router table - the key is to get yo bad self a perfectly flat and true platen to attach the fingerboard to (screws, tape or vacuum clamp) and run it past the bit. I use a 2" thick x 30" long piece of black limba that I thickness and true up every so often.

I have tried milling pre-slotted boards, and it is a recipe for bad chip-out. So I radius first, then slot - always.

Share this post


Link to post
Share on other sites
bit1.jpg

I notice that at the bottom of the cutters - at the widest part of the bit - the corners are knocked down, and this reduces the total cut depth to less than 2". Maybe this is just because of the small radius making the bit really wide at the bottom, and you wanted it to fit inside the hole in the router baseplate, but router tables have no such restrictions.

I would need a full 2" of cut depth to make it work for me (I regularly radius bass fingerboards that approach 4" wide). So for a 12" radius bit and 2" cut depth, the radius should extend to the bottom of the cutter blades, and the diameter at the widest part of the bit should be 21.23mm.

Share this post


Link to post
Share on other sites

I sketched up a design for converting a table saw into a radius sander last week, although the problem lies in how to attached abrasive to what is essentially a inner cross-section of a torus :-\

Epoxy/latex and abrasive grit?

Share this post


Link to post
Share on other sites
I think the results would be even better in a router table - the key is to get yo bad self a perfectly flat and true platen to attach the fingerboard to (screws, tape or vacuum clamp) and run it past the bit. I use a 2" thick x 30" long piece of black limba that I thickness and true up every so often.

Got me to thinking you could build a plywood box for the router (instead of using wood)and tape the board level with the top edge (vertical posistion). Gives you some surface area to keep the base of the router flat as you work.

Share this post


Link to post
Share on other sites

I think that a router table and a push block with an L-shaped guide to hold the workpiece against the fence and to push it along would be more than sufficient :-D

Share this post


Link to post
Share on other sites
I gotta get me one of these.

For clarification, one bit does the job?

If all you're ever doing is one radius - then yes. :D

:D

Share this post


Link to post
Share on other sites

×
×
  • Create New...