Modifying a end mill holder

J

jmarkwolf

Active User
H-M Supporter Gold Member
I want to start using Hougen type annular cutters in my mill.

The shank on the typical annular cutter doesn't readily accommodate a drill chuck or a collet, due to the two flats on the cutter shank for set screws. I've been successful using a 3/4in collet but I'd rather not worry about slippage, etc.

The only ready made tool that I've found on the web is by Accusize Tool for $66, but the reviews are terrible.

Seems like an economical alternative would be to modify a 3/4in end mill holder to accommodate the cutter. The mods required would be to remove the beveled nose of the end mill holder, and add a set screw 90 degrees from the existing set screw.

I searched the forum on this subject a found a reference to one guy that was successful doing this but he didn't elaborate on how he did it. If the end mill holders are hardened, and I'd need to purchase expensive specialized tools to do this, it would make the prospect less tantalizing.

Another alternative would be to make an adapter with a straight shank on one end, for a collet, and a precision bore on the other, with two set screws, for the annular cutter. Could probably be made from CRS.

Can anyone advise?
 
I bought the Accusize annular cutter holder to use with the lathe despite the bad reviews I have not had a problem with mine. All I did was replace the 2 set screws. I have not tried using the ejecting pin feature though, probably never will. Not sure if I just got lucky.

I modified an end mill holder some months ago to use as an extension for my slotting saw arbor. Mine is just a cheap China one. Never tried drilling and tapping one but I did shorten the nose & remachine the bevel. I was able to machine it just fine. If anything it's probably only case hardened, for the cheap import ones anyway. My slotting saw arbor was much harder.

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To add, all the arbors I have modified were only case hardened. I modified a boring head arbor to use with my big fly cutter. It was only case hardened too. I was able to single point external threads & drill & tap it also.

www.hobby-machinist.com

My New (Big) Fly Cutter

I do have a 2.5" facemill which I use a lot but I also like fly cutters as they give a better surface finish (IMO). The FM can hog out more material than a fly cutter though. On my project list was to make a fly cutter that will cover up to 6". I didn't want to make a big conventional styl fly...
www.hobby-machinist.com www.hobby-machinist.com
 
I have an R-8 annular cutter arbor for the mill, what does yours use?
 
Modifying an end mill holder for annular cutters is not that difficult. For my mill (30 taper)
I used a 3/4" holder and turned the end down in length till the setscrew was in the right position.
(No need to drill and tap, you only need one setscrew.) I also turned the diameter down to a little
less than 1-1/2". The material was hard but not so much so that I couldn't cut it with a good
insert.

Also made a holder for the lathe (MT4) from a blank (machinable) morse taper arbour. Mount it
in the headstock with the proper adapter and drill and bore to size and then drill and tap for the
setscrew...
 
I modified a 3/4" end mill holder for annular cutters. It is case hardened which extends about 1/16", I did not cut off the nose, but it could be done with carbide inserts. I started the holes with a HSS center drill, and then drilled through with a cobalt drill, then threaded with a HSS tap. Use two set screws either 3/8 or 7/16 at 90 degrees. You will need to use a fine file or small dremel drum sander to debur the holes on the interior otherwise the annular cutter will not slide in. I just helped someone else who was doing the same thing with a Sowa R8 holder, otherwise buy an inexpensive one for $20. I have the Accusize in a MT3 version for the lathe, not impressed with it, I would have been better off buying a 3/4" MT3 end mill holder and punching two holes in it.

www.ebay.com

3/4" END MILL HOLDER R8 ADAPTOR TOOL MILLING BRIDGEPORT ^[ | eBay

Work on all Bridgeport, ENCO, JET, SHARP, Alliant and ACER Milling Machine with R8 spindles. SHARS PRECISION R8 3/4" END MILL HOLDER NEW. Ground shank and hole, heat treated for double accuracy. You may ask for freight cost before buying tools.
www.ebay.com

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I do not remember paying this much for the flood cooling one, and another one on Ebay. It sounds like you got the end mill holder mod down, so just an FYI.

Amazon.com: Annular Cutter Arbor,R8 Spindle : Industrial & Scientific

Buy Annular Cutter Arbor,R8 Spindle: Annular Cutters - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
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www.ebay.com

R8 Shank Magnetic Arbor Drill Bridgeport Milling Machine Annular Cutter Adapter | eBay

2 Grub Screws to hold in Rotabroach cutter To fit Bridgeport Mill machines We have also got MT2 & MT3 Arbors in stock If you require anymore sizes any questions please dont hesitate to contact us Check out my other items...! We also buy surplus engineering tools and equipment. Large quantities...
www.ebay.com
 
jmarkwolf said:
I searched the forum on this subject a found a reference to one guy that was successful doing this but he didn't elaborate on how he did it. If the end mill holders are hardened, and I'd need to purchase expensive specialized tools to do this, it would make the prospect less tantalizing.
Can anyone advise?
Click to expand...
Possibly jmarkwolf is mentioning my previous answer on this question, so here's what I found: I cut the holder back on the lathe with a common carbide toolbit. I don't think my copy is case-hardened, as it was pretty much the same cut all the way, nor was the holder hardened, I think, but is probably the high-carbon "Chineseum" steel that many such items seem to be made of. It wasn't an easy cut but not difficult, either. I cut until the flat on the annular cutters would fit fully under the set screw and the shoulder on the cutter seated on the face of the holder.. On mine, the screw is a 16mm screw and so far it has been sufficient to have just the one original setscrew, although the cutters are designed for two setscrews 90 degrees apart. Drilling and tapping for a matching setscrew might be a challenge.

Here's a before-and after:holder.jpg
 
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