Regrind milling wheel cutter for dovetails

Adair Orr · Jan 12, 2017

Hello all,

I'm trying to make multiple dovetail dies for a sheetmetal powerhammer. I'd like to gang up several blanks of 2x2 stock and cut the dovetails all at once. I was advised to have a wheel cutter reground, perhaps even an old, dull cutter found on fleabay since it will require grinding regardless. Can anyone advise me on the parameters of tool I should be looking for. I need to make a 1" tall dovetail with a 10 degree angle. I would also like any recommendations for a shop that would take on the grinding work.

I have access to a large WWII era Cincinatti Mill with a vertical head at a local machine shop. Will I require a certain type of arbor? Any insight would be appreciated.

-Adair

johnoder · Jan 12, 2017

Probably best would be to rework an end mill that was large enough

I have yet to figure out if you are cutting one side at a time or not

If one side at a time, a "wheel" cutter could also work but would require some sort of stub arbor to hold it, where an end mill would not

Probably too big but somewhat cheap....

http://www.practicalmachinist.com/v...ed/36-very-large-end-mills-2-diameter-329553/

enginebill · Jan 12, 2017

It looks, to me, that you could set your stock on a 10 degree angle and make a square cut, no need for a precision fit.

Adair Orr · Jan 12, 2017

Engine Bill, You are correct. For the die holder shown in the photo, the shoulder of the dovetail need not be a specific angle. However, on other machines of this type operators want the ability to use shims under the shoulder.

John, I've attached a copy of a 2-1/4" end mill, 1-1/4" shaft from fleabay. HSS. Might this be a good candidate for a regrind?

-Adair

johnoder · Jan 12, 2017

Adair Orr said:
John, I've attached a copy of a 2-1/4" end mill, 1-1/4" shaft from fleabay. HSS. Might this be a good candidate for a regrind?

-Adair

Looks ideal. You might check if the big mill has a 1 1/4" end mill holder

enginebill · Jan 12, 2017

You can buy 75 degree dovetail cutters, that might still allow for shimming.

[486] · Jan 12, 2017

10 Degree Taper Angle per Side, 1/2 Inch Tip 4153268 - MSC

they make tapered end mills

prolly find them much cheaper than MSC with ten minutes of searching

Adair Orr · Jan 12, 2017

[486]- I will look, but they will have to taper the other direction to work for my application.

John, The bulk of the cutting will be on the side of the cutter, does that call for a different type of cutter than the last image I posted?

One nice thing about this large cutter is that it would work for my larger power hammer dies as well.

-Adair

[486] · Jan 12, 2017

Ahh, I see.

I might have something like that, I'll check for you.

[486] · Jan 12, 2017

Found a couple, bought a bunch of stuff at auction and I really think they liked finding work for their toolmakers, nearly everything had carbide brazed onto it, haha

Smaller shank one is about 15 deg per side, and larger shank one is about 10 deg per side. I was only able to eyeball them against the protractor.

Larger is 1.250 shank, smaller is 1" shank
The corner radius (like 1/8" rad) is probably a bit excessive, and there are some chips in the carbide.

$40 shipped for both of them?

johnoder · Jan 13, 2017

Won't be ideal since it will be a taper regrind of a straight end mill (geometry considerations) but the big mill and its 1 1/4" end mill holder won't have any trouble making chips with it.

Adair Orr said:
John, The bulk of the cutting will be on the side of the cutter, does that call for a different type of cutter than the last image I posted?

-Adair

stephen thomas · Jan 13, 2017

My kid brother made some parts like that. He used a shaper for the DT's.

Starting the sowblock dovetails for one of his hammers

smt

Monarchist · Jan 13, 2017

stephen thomas said:
My kid brother made some parts like that. He used a shaper for the DT's.

Near-as-dammit any angle possible - and with no significant fuss about it.

Shapers can be had right cheaply, too.

Reduced cost of tooling could soon pay for one and then some.

"I got mine"....

Bill

carla · Jan 13, 2017

I'd concur with Stephen........unless you are thinking in terms of a production setup for a great many pieces, the shaper is a more practical choice for the generality of dovetail parts. (been there, done that, its easy work, actually)

cheers

Carla

sfriedberg · Jan 13, 2017

A shaper is definitely an appropriate tool for this job. However, so is a horizontal mill. You can buy new/used single angle cutters, or take a plain cutter with coarse & deep teeth and regrind it as an angle cutter.

gbent · Jan 13, 2017

Grinding anything other than straight flutes on a dovetail cutter requires either real fancy grinding equipment or a deft touch with a 4 1/2" angle grinder. If you really must mill the dies, I would suggest buying the closest angle straight flute dovetail cutters you can and modify the angle as necessary.

I concur with the shaper suggestions.

On the other hand, does it matter much? They will probably forge the keys and drive them hot for final sizing anyway, then touch them up cold and drive them in with a sledge.

michiganbuck · Jan 14, 2017

Checking angle is not easy on the sharp edge.. not bad with using a shadow graph.. but I have found spinning a circle grind (just like OD grinding)to get angle correct.. then bring clearance angle up to just make a straight (with no fish tails at the end) then to sharp is the best to make the altered and even resharpen an existing angle.

Think Stephen Thomas posted a photo of on-a-riding-finger shrapening on an older thread.. that is perhaps the best way.

Adair Orr · Jan 18, 2017

Thanks all for the input. I'm not sure exactly how best to proceed. There is a lot of tooling to be made over time as I continue learn how to employ this metalshaping hammer.

I don't have a shaper, and have had to pass up on free ones for lack of space in my shop. I'm determined not to be so buried by tools that I can't actually make anything. Perhaps I just need to send the stock to someone with a shaper.

I thought the milling cutter would be a good compromise that would allow me to make the blanks on a machine nearby, then I could machine, heat treat, and dress the striking end of the tool at my shop as needed. These are not giant dies like the Beaudry hammer posted, and they are not secured with tapered wedges as most forging hammers, so I would like the dovetail angle to be precise.

-Adair

Leg17 · Jan 18, 2017

It is a good idea if you have access to a horizontal mill.

Paolo_MD · Jan 18, 2017

Adair Orr said:
Thanks all for the input. I'm not sure exactly how best to proceed. There is a lot of tooling to be made over time as I continue learn how to employ this metalshaping hammer.

I don't have a shaper, and have had to pass up on free ones for lack of space in my shop. I'm determined not to be so buried by tools that I can't actually make anything. Perhaps I just need to send the stock to someone with a shaper.

I thought the milling cutter would be a good compromise that would allow me to make the blanks on a machine nearby, then I could machine, heat treat, and dress the striking end of the tool at my shop as needed. These are not giant dies like the Beaudry hammer posted, and they are not secured with tapered wedges as most forging hammers, so I would like the dovetail angle to be precise.

-Adair

Adair,
Too bad you don't have room for a shaper or a planer. Anyhow, if you have a sturdy and large enough vise, and you find either large 60°-75° cutters for an horizontal mill, or decent size 60°-75° cutters for the vertical head, you could machine the dovetails in two setups: first with the vise horizontal, then tilted to compensate for the deficiency of angle in the cutter (i.e. 20° for a 60° cutter, 5° for the 75° cutter).
However, be very careful and don't hog, because the setup will be rather flimsy.
If you were to regrind a cutter, I'd suggest doing so with a horizontal mill cutter, since you won't lose too much chip-load capacity and you don't weaken it much.

Just my ignorant two cents.

Paolo

Regrind milling wheel cutter for dovetails

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