Official Luthiers Forum!

Hi
I am trying my first complex type of inlay and I am having a problem with bits breaking. I am wondering if any of you have tips for working with these very small bits and what bits seem to work best for you. I do have the stew mac router base and I have tried to take what I thought were relatively shallow passes with the bit so as not to over stress it but it still snapped. Thanks
Bob

Don't try to route too much at once. I start with a slightly larger bit to get close to my line and then put the smaller bit it to get the details. Recently I have been using a different brand of bit that seem more durable. I really like them for all dremel routing....inlays rosettes etc
They are sold by micromark

http://www.ares-server.com/Ares/Ares.asp?MerchantID=RET01229&Action=Catalog&Type=Product&ID=80245

_________________
Andy Z.
http://www.lazydogguitars.com

Talk to your dentist about used dental burrs. They only use them once and they're still pretty sharp. I've never had one break. I think they work great in a Dremel with the StewMac router base.
Terry

_________________
It's not what you don't know that hurts you, it's what you do know that's wrong.

I second the suggestion on going big first, then use the smaller bits for the edges. I go by one simple rule, use the largest bit you can.
Of course, there are some that hit the edges first, then the center, which, depending on the size of the cavity, may make more sense.

The diamond cut bits do leave a very smooth edge (which gets filled), but they clogged up really quick (for me anyway). I've used the diamond cut bit in the past, but downcuts work best for me:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=170235958147&ssPageName=STRK:MESE:IT&ih=007

Thanks guys, the problem I am having is that the inlay consists mostly of really fine line lettering not suitable for a large bit. I will check with my dentist, he has been really good about supplying me with used dental picks that come in handy for a lot of things.
Bob

My guess is that runout and lack of RPMs could be significant. The smaller a bit, the less tolerance it has for a lot of runout. Dremels have a -lot- of runout. If the RPMs are too low then it might not be clearing chips effectively, either, as humans can only move so slow smoothly to account for inadequate RPMs. Carbide is also going to snap a lot easier than HSS in a high-runout situation.

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Following up on what Bob said, once I moved from Dremel to Foredom, bit breakage became non-existent (I was finally able to feel a bit get dull - of course, this was a lesson quickly learned).

For fine lettering, I like to plunge, which is why the fishtail ends work great. In fact, depending on the inlay, I plunge a LOT.

Might I ask what kind and size bits are you using. Spiral downcuts? I have a SM precision base and the one thing I did was to change the base to a plexi one. Really helps with seeing where you are routing . I also made a vacuum attachment for the dremel out of hose that connects to the shopvac. Although it's just taped to the dremel it works great. I also have the dremel and vac hooked up to a single foot switch. The vacuum is in another room with a micron filter for pearl dust as I use it for the cutting board too.

Aaron
I am not really all that familiar with fordom equipment. What kind of plunge set up do you use? Could you possibly attach a link showing the equipment.
Thanks

Simple Stew Mac setup with the Foredom Flex Shaft. Plunging as it relates to inlay is not equipment, but technique. Just lean it back and lift the bit. Takes getting used to, but once you got it. . .

too deep of cut, too much leading pressure, wrong RPM will lead to the bit over heating and snapping. Use as large of bit as possible for major material removal and extra fine to clean up only

Bob,

If I recall correctly, the Dremel used to slow down rpm's when routing. As already stated, proper rpm can be a contributing factor.

I didn't want to drop the $$$ on the Foredom because I thought that a Dremel with a Flex shaft would be the same thing. Its not. Besides the power, another benefit I found with the Foredom is the foot control (which you could probably set a Dremel up with). Like computers, I don't know how I did without it.

I hope I explained plunging enough, have you tried it yet?

Foredom is the ticket in my opinion as well. There is a world of difference in HP and no comparison on the flex shafts.

That said the Dremel mulipro will produce more RPM but at much less HP.

It really does not matter which you use both will do a good job but at different rates. No matter which you use, don’t try to use a .03" dia. bit to hog out a large area. use the largest bit that gives some leeway and finish corners and tight areas with the fine bits. One it will avoid breakage and two it extends the life of the bit.

John Hall's air powered die grinder setup is the way to go, IMO. High RPM, and even a modest compressor will keep up. Pair that with downcut carbide end mills (two flute, square), and you've got high quality, clean cuts, controllable, no burning. Lovely.

If I could rig a good foot control air valve and keep the grinder from getting so cold to the touch I would almost agree

Aaron, I was doing plunge cutting the way you described it, I just didn't think of it as plunge cutting because it was different than a plunge router. Tunnel vision on my part. I did order the stew mac set of 6 dremel bits that I can experiment with. I just plunked down a bit on some new stuff so the fordom might have to wait a bit but I guess it will go on the list. I did try Frank Ford's idea of using a little tape flag on the bit to get rid of routing debris and it works like a charm, no vacuum needed.
Thanks for all of the replies.
Bob

Here's a link for some bits.
http://www.endmilldiscount.com/end-mill ... t-sr-2.htm
I don't think the foredom is going to keep you from breaking bits. I have no problem with the dremel in the picture and neither does alot of others. Like the others have said, larger bit to hog out what you can then go to the 1/32" bit. Don't try to go fast or try to take too much at a pass. Those bits are fragile. As a matter of fact don't try and go fast at any stage of inlay if you are a beginner. It takes time and practice and then the speed will come. And that's from layout to finish sanding. As for beginners I always suggest you purchase the Larry Robinsons DVD's as they are excellent and worth every penny. The money would be better spent on them before the foredom.

I would second everything Chris stated above. Nice setup with the vacuum, BTW. And I would third Robinson's DVD's - and his updated version of his book (even if you have the old one).

As for bits, you can see from this thread, to each his own, and there is really no right or wrong (there is safe and unsafe, though), its what you feel comfortable with. I use fishtail downcuts for specific reasons. The link that Chris provided for Performance Micro Tool bits - PMT is good quality, but they don't have readily available downcuts. However, their upcuts are top notch, and I've used their 1/8" to hog out major channels, then switched to my smaller downcuts (I sell more 1/32" bits than I do 1/8" bits, wonder why?).