# Sharpening spiral bits?



## Shandit66 (Feb 2, 2010)

I'm not sure this is possible, hence my question.
I have several Up spiral, 1/2" bits, that are not as sharp as I'd like them. 

1 - are there methods were I can sharpen these at home? Jigs etc.
2 - I'm sure there are sharpening services. What's a decent rate for getting them done?
3 - There's a huge amount of industrial "mill ends" available on eBay. Prices get below $10/pcs for larger batches. Whats the difference between a mill end and a router bit?

Thanks for the help


----------



## Sawdust Don (Nov 1, 2012)

I have not examined the spiral router bits yet, but very familar with end mills.
To sharpen the sides of the flutes, when done reduces the diameter.
This is best done with an air bearing fixture-Weldon is a common brand, generally used on a tool and cutter grinder, but can be used on a small surface grinding machine.

There are smaller machines for this work also, with the sliding fixture built in, though, most anyway to go there can be expensive.

Don


----------



## Mike (Nov 22, 2004)

Olaf, end mills are designed for working with metal; router bits are designed for working with wood. There are big differences in what you are trying to accomplish, stick with router bits.

Spiral bit sharpening is best done by the pro's. Check your Yellow Pages for tool sharpening. Whiteside Machine in NC, USA has excellent sharpening services. You will find others too. Remember that bits spin at very high rpm so you sure do not want one out of balance.


----------



## Sawdust Don (Nov 1, 2012)

Mike,
I suspect that some endmill styles, have the same edge profiles/spirals as what is being sold as wood router bits.
Hundreds of types for ferrous/non ferrous, plastics, ect.
The problem would seem more to be in shank sizes. Example-most common shank for 3/16" endmill-3/8" shank.

Don


----------



## Phil P (Jul 25, 2010)

Hi Olaf

Sharpening spiral bits takes some pretty sophisticated kit to ensure that the balance isn't knocked to heck. in the past when I used them they always went out to a specialist engineering service who would send the sharpened ones back dipped in protective plastic with a little ticket stating the new diameter (which reduces every time you sharpen them).



Sawdust Don said:


> The problem would seem more to be in shank sizes. Example-most common shank for 3/16" endmill-3/8" shank.


Depending on the manufacturer of your router that can be overcome, to an extent. For example, routers such as the deWalt DW625 and Festool OF2000/OF2200 have a wide range of collets available (6mm, 8mm, 10mm, 12mm, 1/8in, 1/4in, 3/8in - getting difficult to source, 1/2in) although you may need to resort to buying from abroad to get the sizes you need. As it happens the Freud FT2000 shares the same design of collet

Regards

Phil


----------



## Mike (Nov 22, 2004)

Porter Cable and Bosch sell 3/8" collets in North America, I know... I have them. I believe DeWalt does too.


----------



## Shandit66 (Feb 2, 2010)

I'm guessing spirals is one of the toughest to sharpen. 
My first crack is to touch up the edges with a diamond blade. Just taking any buildup off helps a lot. But to actually sharpen is different. 

Reducing diameter doesn't bother me, even if its a lot. I had assumed that just he cutting surface is ground so the collet diameter stay constant. I.e. I'm missing the points about different collets 

As for end mills, they must cut sideways just like router bits, albeit through metal. I've frequently used carbide metal cutting drill bits on wood, without any issues. Thy last a bloody long time and cut extremely well. I'm assuming something similar with router hits/end mills.


----------



## Phil P (Jul 25, 2010)

Shandit66 said:


> I had assumed that just he cutting surface is ground so the collet diameter stay constant. I.e. I'm missing the points about different collets


Hi Olaf

When spirals come back from a sharpening service they haven't ground the shanks at all - they need something to hold onto the cutter whilst they are grinding it. The point about collet sizes is more to do with the way solid carbide tooling is manufactured - my own experience is that many industrial tooling manufacturers only deliver tooling where the shank and body start out the same diameter - so an 8mm cutter will have an 8mm shank, 1/2in cutter will have 1/2in shank, etc. For CNC machinery with ER-32 or ER-40 collets this isn't an issue as collet sizes go up in increments of 1mm (and are compressible by 1mm so you can have a continuous range) 



Shandit66 said:


> As for end mills, they must cut sideways just like router bits, albeit through metal.


I've found two problems with them; they don't plunge well - and for cutting mortises, etc on a a plunge router that's a must; and some designs don't have a sufficiently deep flute to clear the waste - timber cutters are generally 1- or 2-flute designs and are supposedly designed with deeper gullets than metal for better waste clearance. The spiral angle on cutters designed for timbers and plastics is often much steeper for better chip removal, too. I suppose it all depends on what you are doing with them

Regards

Phil


----------



## Dmeadows (Jun 28, 2011)

Shandit66 said:


> Reducing diameter doesn't bother me, even if its a lot. I had assumed that just he cutting surface is ground so the collet diameter stay constant. I.e. I'm missing the points about different collets


Depends on what you are using them for. Dadoes and rabbits and the like you can just make another pass. If you are making box joints with a jig, it can really mess up the fit!

The point on collets, is the collet must be the same size as the shank of the bit!( ie 3/8 shank needs 3/8 collet, 1/2" shank 1/2" collet, 8mm shank 8mm collet, etc) this can also be done with adapters, though many members don't like using adapters as there is greater chance of the bit slipping. Other, including myself have used them with no problem.


----------



## Shandit66 (Feb 2, 2010)

Phil P said:


> When spirals come back from a sharpening service they haven't ground the shanks at all - they need something to hold onto the cutter whilst they are grinding it.


Phil,
That makes sense and what I'd thought, because the 1/2" shank needs to fit back into the colette. 



Phil P said:


> I've found two problems with them; they don't plunge well - and for cutting mortises, etc on a a plunge router that's a must; and some designs don't have a sufficiently deep flute to clear the waste - timber cutters are generally 1- or 2-flute designs and are supposedly designed with deeper gullets than metal for better waste clearance. The spiral angle on cutters designed for timbers and plastics is often much steeper for better chip removal, too. I suppose it all depends on what you are doing with them


I don't need any plunge capabilities - and should explain. 
I have a 3 hp router mounted on the cross-slide of my very large metal lathe.

The wood rotates very slowly (~ 5-10 rpm - depending on the diameter). I can cut the patterns into the wooden bowls, platters etc using the router. With the cross-slide I control the cut manually: left/right, in/out, with speed adjust on the lathe, I control the feed rate. Hence I don't really plunge the bits in, its almost always side cuts.

This works really well for rough cutting green wood, almost as well for seasoned wood. Especially well for wood with multiple densities, such as spalted maple (which can be very hard and soft on the same piece.)

Its just very messy - the stuff flies everywhere.
This is all pretty rough shaping, not fine finish work. It all gets sanded a lot once the piece has the right shape.

I've tried spiral vs straight bits. The spirals remove wood quite a bit faster. But I have broken a couple when I've screwed up. But all that cutting causes a fair bit of wear, hence my search for ways to sharpen. 

Your comments on flute design are very welcome and worth serious consideration. I can buy the end mills a LOT cheaper, in large batches.

If they don't work, then I'll likely go back to straight bits, which I can sharpen.

Thanks for the feedback.
Olaf


----------



## Phil P (Jul 25, 2010)

Shandit66 said:


> I've tried spiral vs straight bits. The spirals remove wood quite a bit faster. But I have broken a couple when I've screwed up. But all that cutting causes a fair bit of wear, hence my search for ways to sharpen.


Hi Olaf

Just something else for you to consider. If you can't get the spirals to work and you are prepared to put up with straights, but wear/cost are a consideration, then take a look at replaceable tip carbide cutters like the three on the right below:










The 12 x 12 x 1.5mm carbide tips on the smallest cutter there (2nd from the right) cost me about £1.50 (US $ 2.20) a pop, or less if you eBay, and give me four "sharpenings" each - so sharpening price works out at £0.75 ($1.15) a time. Initial purchase prices are, however, pretty steep (the most basic non-bearing 19mm diameter x 12mm high cutter is £26 or US $ 39). 

For me, at least, they have two big advantages - 3 or more times or more the life of a brazed carbide tip and constant diameter when rotating tips. I'm in the UK so I don't know the comparative costs in the USA, but here at least they make a lot of sense for intensive machining.

Regards

Phil


----------



## Sawdust Don (Nov 1, 2012)

From many auctions, I have ended up with a couple hundered pounds of end mills!

Now just to show a machine that is capable of sharpening anything, and I mean anything including circular saw blades, planer blades to 24", and chisels for woodworking, along with router bits.
This 1942 Cincinatti #2 tool and cutter grinder will do it.
A draw back is it weighs 2000lbs. Often these can be found for a few hundred dollars, well, the size and weight is a factor there.
shown here set up for lathe finishing cutters, and jig bore boring bars.
The regular workhead will handle spriral cutters down to 1/4". Smaller cutters are best done using the air bearing workhead.
Both primary and secondary cutter edges, can be sharpened, or changed to suit the material being cut.
This is probably the most important support machine I have.


----------



## Phil P (Jul 25, 2010)

Hi Don

How much do green silicon carbide wheels (for TCT) cost for that?

Regards

Phil


----------



## Sawdust Don (Nov 1, 2012)

Phil,
Green wheels are pretty cheap, probably as low as $15 for a 4" cup wheel.
But, green wheels are a bad choice. The reason being, they micro fracture the carbide.
The wheel shown being used is a diamond cup. These are much better, grind cool, and leave a non fractured edge. Around $90 for that wheel, they last nearly forever, I have had that one for 20yrs.
The other most useful shape is a diamond dish wheel.
For steels, I use aluminum oxide wheels mostly, but have a couple of cubic boron nitride wheels-those are the most expensive.

Don

I will add on green wheels. They work fairly well on hand grinding, but, Its best to final finish the edge with a diamond lap, to clean up the edge, otherwise the edge life will be reduced from the green wheel problem.


----------



## bobj3 (Jan 17, 2006)

HI

note sure why any one would sharpen router bits,if you are in the states they are cheap now days..

1/2" carb.spiral bits go for $15.50

The bits below are so sharp you need to wear cloves to install them,now that's sharp,they are the best bits I have found on the net..  and the price is great with FREE shipping on top of that...in the states..and he is a quick shipper..

69 084 Onsrud Double Edge Solid Carbide Downcut Chipbreaker Finisher Router Bit | eBay

69 075 Onsrud Double Edge Solid Carbide Upcut Chipbreaker Finisher Router Bit | eBay

High Speed Steel Router Bits, Carbide Tipped Router Bits items in LMT Onsrud Router Bits and Blades store on eBay!

57 281 Onsrud Solid Carbide Double Edge Downcut Spiral Wood Rout | eBay


..........


----------



## Sawdust Don (Nov 1, 2012)

That is a good point Bj.
Even owning a machine that can sharpen them. It would take at least and hour to set up and grind a single bit.
It starts to make more sense regrinding, when going through multiples of bits, such as on tough materials.
Then once the machine is set up. each bit could be done in minutes.

Since I am new to wood routing, I have not found the need for those bits yet.

Don


----------



## Phil P (Jul 25, 2010)

Thanks for the information, Don. I've never had a yearning for that type of grinder, at least not so far, but maybe in the future, though 

Regards

Phil


----------



## Mike (Nov 22, 2004)

Olaf, taking a look at the Betterley Stacc-Vac might generate some ideas you could use on your lathe.


----------



## Shandit66 (Feb 2, 2010)

Looks like I have some options to check out. They're all cheaper than the $40 at the local supplier. Thanks for all the feedback! 

Here's a couple of pics from the set up. Yes, I totally butchered the router, but its only a $50 Power Fist. I couldn't do that to my Bosch.


----------



## Phil P (Jul 25, 2010)

Hi Olaf

Having seen the set-up I can see what your problem might be. Any square cutter will be doing a massive amount of the machining with its bottom tips alone. No wonder they are wearing out! Why not get a couple of cheap core box bits like these from George Hsu and try them? Because they will be cutting over a greater part of the cutting edge they could last quite a while longer and it should be possible to touch them up a few times with a diamond hone before they go off for sharpening. 

I still think that a turning rest and a good long bowl turning chisel would remove material faster, though

Regards

Phil


----------



## brucenelson (Jan 7, 2012)

Shandit66 said:


> Looks like I have some options to check out. They're all cheaper than the $40 at the local supplier. Thanks for all the feedback!
> 
> Here's a couple of pics from the set up. Yes, I totally butchered the router, but its only a $50 Power Fist. I couldn't do that to my Bosch.


That there is quite a good looking metal lathe, with risers for turning large diameters. It is capable of cutting screw threads, is gears are available to connect the spindle to the quick change gearbox. It also needs a thread indicator dial, but a machinist would probably kill for that machine.

The moral of the story is that new spiral ground bits are so reasonably priced, and are produced on CNC grinding machine that don't require manual operation. The difficulty in manual grinding of spiral cutters is why practically nobody does this anymore. This is why old tool and cutter grinding machines are so cheap.


----------



## Shandit66 (Feb 2, 2010)

Thanks. It's a ~1925 American Tool Works lathe that I picked up for $400 a few months ago. Fair ly functional but very dirty and I need of TLC. Due to the risers the feeds don't work right now but I have a dc motor and controller ready to hook up. The cutter is now way too low so there's no way it will cut metal at the moment, but hats not the plan any way. 

On recommendations above, i bought some bits from George Hsu on eBay and will tru them out. I've sharpen up my straight bits and they'll do or a while.


----------



## WayneMahler (May 17, 2012)

Mike said:


> Porter Cable and Bosch sell 3/8" collets in North America, I know... I have them. I believe DeWalt does too.


Mike
Thanks did not know Porter Cable and Bosch sold 3/8" collets. Nice to know, missed a few good deals due to the lack of this knowledge.:agree:


----------

