Reshape B&S 9 end mill holder for boring head?

katou · Nov 15, 2017

I am looking at getting a boring head for my Gorton 9J, which has a B&S 9 quill.

The boring head requires a 1-1/2 adapter 18 tpi.

I've checked Ebay and Travers for such a beast with no luck.

I have several #9 end mill holders that are big enough to cut down to fit. Is this a reasonable idea?

File test indicates the holders are hardened. Can I just anneal them and cut/thread? I've never tried working with already hardened steel before.

Katou

Monarchist · Nov 16, 2017

katou said:
I am looking at getting a boring head for my Gorton 9J, which has a B&S 9 quill.

The boring head requires a 1-1/2 adapter 18 tpi.

I've checked Ebay and Travers for such a beast with no luck.

I have several #9 end mill holders that are big enough to cut down to fit. Is this a reasonable idea?

File test indicates the holders are hardened. Can I just anneal them and cut/thread? I've never tried working with already hardened steel before.

Katou

I just mount my Chandler-Duplex straight-shank ones IN a 3/4" end-mill holder. Or an ER-40.

Suggest you scout for a shell or face mill holder ELSE a short arbour with a #9 B&S arse-end.

Should be more meat on either where you will need it for the mod than on the average side-lock end-mill holder.

Or.. JF make it from scratch. B&S tapers are not hard to do.

Pre-hard 4XXX as-had should be fine.

johnoder · Nov 16, 2017

File test indicates the holders are hardened. Can I just anneal them and cut/thread? I've never tried working with already hardened steel before.

If you can't file it, you sure won't have much luck threading it

Following assumes carbon tool steel

Take it up to visible red on that end and cool very slowly - like in a bucket of sand

Makes all the difference in the world

batw · Nov 16, 2017

Monarchist said:
I just mount my Chandler-Duplex straight-shank ones IN a 3/4" end-mill holder. Or an ER-40.

Suggest you scout for a shell or face mill holder ELSE a short arbour with a #9 B&S arse-end.

Should be more meat on either where you will need it for the mod than on the average side-lock end-mill holder.

Or.. JF make it from scratch. B&S tapers are not hard to do.

Pre-hard 4XXX as-had should be fine.

i second the motion, not hard to do at all.....

Illinoyance · Nov 16, 2017

If I remember correctly BS9 takes up to a 3/4" collet. Use a collet in the spindle and a 3/4" shank on the boring head.

4GSR · Nov 16, 2017

Back when we had our Gorton 9J's, which had No. 10 B & S tapers, we made a soft shank that mated with the B & S taper for the first 2" of length on the big end. And on the end, we threaded it to fit the 1-1/2-18 thread in the boring head. This shank was inserted into the spindle, snugged, then the boring head was threaded up until the back of the boring head shouldered against the face of the Gorton spindle. Doing this, eliminated the awful chatter we were getting trying to use a straight shank in a arbor. We also had a 8-1/2D head we did the same thing with it too.

CountryBoy19 · Nov 17, 2017

Just make one... assuming you have a lathe with taper attachment... I have an Index mill with B&S #9 and I made my own arbor exactly as you're saying (1-1/2-18 thread) for a boring head. I used ETD-150 instead of 4140 PH because it gives equivalent hardness but cuts a bit nicer. I had no problems cutting a good taper on a clapped out SB light 10 lathe.

I now have a much heavier lathe and I'm anticipating making many more arbors and such as the need arises throughout the years.

Paolo_MD · Nov 17, 2017

Katou,
I don't want to sound condescending, since you likely already know it. But the best way to proceed is to cut everything between centers, so that you're sure that the thread is perfectly aligned with the shank and you can remove the piece as many times you want to test the threads, as long as you do not disturb the dog.

Paolo

katou · Nov 17, 2017

Thanks to all. No worries Paolo, I'm hard to take offense, especially when someone's trying to help.

I will make the piece as suggested.

If I used pre-hardened steel, I'd need a tool post grinder yes?

If I harden it, it must be ground afterwards to eliminate distortion which might have arisen during the quench. Correct?

Katou

ezduzit · Nov 17, 2017

How about cutting down one with a larger taper shank?

JST · Nov 17, 2017

katou said:
....

If I used pre-hardened steel, I'd need a tool post grinder yes?

.....

Katou

The 4140PH can be cut with carbide easily, HSS would work, but does not keep an edge well when cutting 4140PH

Grinding would do a good finish, but depending on your lathe, you may be able to get a nice finish. I rarely grind any tapers for my own use, a fine feed finish is good enough.

Paolo_MD · Nov 17, 2017

Katou,
In my opinion, pre-hardened stock is not strictly necessary: you aren't going to screw-on and unscrew the boring head and you better have the taper shank wearing more than the spindle taper.
Personally, I would consider leaded steel, which is easy to machine providing a beautiful finish. Perhaps, in 15-20 years you'll need to cut another one because this one is worn out by daily usage. So what? You already know how to cut it and, possibly, by then you'll be using other machines anyhow.

Paolo

PS JST is spot-on about machining pre-hadened stock: personally, I'd do the rough-cutting with regular carbide inserts (or brazed carbide) and either switch to very sharp HSS or to lapped carbide inserts for the finishing cuts.

awander · Nov 17, 2017

Paolo_MD said:
Katou,
I don't want to sound condescending, since you likely already know it. But the best way to proceed is to cut everything between centers, so that you're sure that the thread is perfectly aligned with the shank and you can remove the piece as many times you want to test the threads, as long as you do not disturb the dog.

Paolo

It's a boring head-how critical is it that the threads be perfectly in line with the taper?

Paolo_MD · Nov 17, 2017

awander said:
It's a boring head-how critical is it that the threads be perfectly in line with the taper?

Not critical at all. Just ugly if it ain't.
The true issues that I failed to explain clearly is that turning between centers allows to remove the piece and test for fit both for the threads (as I mentioned) and for the taper shank (I forgot to mention this in my earlier post).

Moreover, even if you were to forego the testing of the taper in the spindle while cutting it, in order to be able to hold the piece in the chuck, you would need at a couple extra inches of stock wasted at the ends. Instead, if you cut between centers, you need a piece of the right length with almost zero waste. True, we're talking of something that is ~1.75" in diameter and not bigger bars. Even so, it's already a few dollars difference as well.

Paolo

Mike C. · Nov 17, 2017

Also, it's a boring head... how critical is it that the shank be hardened. Not going to be taking huge bites with that, anyway. I'd either get a straight shank arbor and put it in an endmill holder, get a straight shyank and grab it in a collet, or just make the whole thing from scratch, as suggested above. It's a boring head, so concentricity is really not an issue, unless you just want to learn how to make something run very true.

JST · Nov 17, 2017

If just boring head, OK, but if for boring and facing, it is best if the thing traverses at right angles to the axis, or it will face a cone.

As long as you are getting that done right, may as well get it reasonably concentric also.

Monarchist · Nov 17, 2017

katou said:
If I used pre-hardened steel, I'd need a tool post grinder yes?

Nah. 4XXX "pre-hard" isn't actually very hard. It cuts cleanly, tends to be stable, and with no need of post-machining heat-treat or grinding, when yer done, yer done.

Mike C. · Nov 18, 2017

"If just boring head, OK, but if for boring and facing, it is best if the thing traverses at right angles to the axis, or it will face a cone."

Doesn't say boring and facing, does it?

Reshape B&S 9 end mill holder for boring head?

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