Machinist's Hammer Head on Sherline Lathe (mill?)

I just heard back from the seller of this head. Unfortunately, it uses 1/2" bars so I would not buy this one.

Be patient, Sir. We will find a good one for a decent price. I have two of these heads; both in superb condition and both cost me less than $100. The rule to note is that there will always be another one and it will be better and cheaper.
 
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I ended up asking him the same question and got the same reply. Oh well.

i did ask the other seller about the bearings, but haven't received a reply. Looking at the pictures, it looks like the listing that you found has set screws that press against a gib, where the listing I found really doesn't appear to have a separate gib. It's more like those screws are holding the entire side on (it's hard to tell from fuzzy jpegs, but something is definitely different).

I do appreciate the help with trying to locate the tool.
 
mikey said:
Eric, you would not believe how much better and easier it is to bore with a Criterion S-1-1/2 head. It threads directly onto the spindle via a 3/4-16 to 7/8-20 adapter so the connection is quite rigid. The ways of the head are much larger and beefier than the Sherline head and the mass of the head is significantly higher. When used with a good cobalt boring bar, the Criterion head is a VAST improvement over the Sherline head.

Boring on the mill is not difficult, although it is a skill like most things. Still, having the right tools is an important thing and I would encourage you to upgrade your head and bars when you can. If you go for an S-1-1/2, Criterion made them to accommodate either 3/8" or 1/2" bars. I highly recommend you go for the A-model that takes the smaller and lighter 3/8"
bars. For bars, go for the M42 set from KBC.
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I'm sure just having a good quality M42 bar would have been a vast improvement!
 
EricB said:
I'm sure just having a good quality M42 bar would have been a vast improvement!
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Cobalt bars are the way to go for a boring head. They are also really good on the lathe. Borite used to make the best ones but they went under. Nowadays, good bars are hard to find. The ones I linked to at KBC are M42 so 8% cobalt. They have a 5 degree lead on them and this is rare to see in a commercial set. Guys would use a surface grinder to put the angle on. This will reduce cutting forces in the bore and reduce chatter. One of the guys on the forum, @tjb, has a set and can give you more info on how they work in a boring head.

These will cut better than carbide. They also finish finer and more accurately than an insert. Sharpening them is simple; just use an extra-fine diamond stone to very gently hone the flat top of the tool. If it is really beat up (sharpen before they get this bad) you can also lightly hone the end. I would not put a nose radius on these beyond what is already there; the 5 degree angle at the end is enough.
 
EricB said:
As I wrote in another thread, Sherline's boring head is the only tool I have from them that did not work as expected out of the box. After a bit of cleanup it does a decent job with light cuts in soft materials using Sherline's boring tools.

That being said, the other day I bored through an iron casting using the Sherline head and an inexpensive brazed carbide bar. It did the job and the bore dimensions are good. The finish was looking good at first but got progressively worse and I couldn't stop the chatter with the lighter cuts to bring it to size.

I've read that boring separates machinists from everybody else. I have a ways to go.
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I found out one reason for the poor finish. When I was cleaning up the machine I found the motor bracket had worked loose. While the boring head was slightly off balance during the job the motor was bouncing around above it. One more thing to add to the checklist!

Eric
 
I've been playing with the Sherline head just to get some experience with the various milling operations.

It's definitely fiddly and hard to make precise changes in diameter, but when I got the setup rigid, I was able to get pretty decent results.

PXL_20220320_203327620.MP.jpg

Nothing quite like the results that Mikey was showing with the Criterion Head, so I'll continue to look for one of those.
 
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