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Wednesday, November 14, 2007

Phase II Quick Change Tool Post Installation

Well, I finally did it. I got off my wallet, and bought a quick change tool post. I purchased a Phase II, Series 100 QCTP set from ENCO. There's already a link to Enco in the right sidebar. The "set" part means that it comes with five tool holders as well as the tool post.

The tool holders area lined up to the right side of the photo. In order to see the photo full sized, just click on it. The first holder accomodates a turning or facing tool, or a small boring bar, as pictured. The boring bar is held centered by a small vee groove in the bottom of the tool recess. Next is a parting tool holder, tool installed. Third is a knurling attachment, which also can hold a left handed facing tool. Fourth is a turning tool holder. It differs from the first only in that the vee groove has been omitted. Last and largest is a monster boring bar adapter which will accept boring bars with shanks as large as 5/8 inch. I don't own a boring bar that large, and doubt I ever will. All of this, less the tools I installed for illustration purposes, for $90.

The fly in the ointment with this tool post is that you have to modify your compound slide to accept the tool post. Or, I should say to accept the tool post mounting stud. The mounting stud that is supplied with the post is 16mm in diameter, and too long. That's it just to the left of the cross slide. I've read that the way others have installed it is to remove the original toolpost stud, drill and thread the compound slide, and you're done. My problem with this method is that you're drilling an awfullly big hole in your already smallish compound slide. Also, if for some reason you want to use the original tool post, you have to drill a too big hole through its' center as well. I opted to install a 12mm stud made from a 12 x100 mm bolt purchased at the local hardware store.

The hex head on the bolt was turned round, then turned to match the flange on the original tool post stud. That's it resting on the right hand side of compound slide. The threaded part is 8mm, pretty wimpy. Remove the original stud by giving it a couple raps with a large shop hammer. It falls out. You might protect the threads by installing a nut on it's end, if you think you'll have a use for it later. Measure the flange carefully in several places. Then reinstall it and use it to hold your original tool post while you turn a matching flange on the new bolt. Then again remove the original mounting stud, and drill your compound slide to accept you new stud.

I used a 29/64 inch bit to drill the hole for the new stud, after much measuring of the new stud, and the drill bit. I also drilled a test hole in a piece of scrap, just to be sure. The problem is that the resulting hole must be about .002" smaller than the diameter of the new stud for a tight fit. If the hole is too small, you can turn down the radius of the unthreaded portion of the new stud to meet requirements, but only so far. Or you can bore the hole out to the right size using your mill and a boring bar, if you've got one. If you make the hole too large, you're screwed. As it turned out, my drill made a perfectly sized hole, and the new stud went in with a few solid taps from a two pound shop hammer. Be careful here. You can damage your slide if you're too enthusiastic.

I then made a bushing for the inside of the new tool post to make up the two millimeter difference in the hole and the 12mm stud. The bushing is just in front of the new tool post. If you look closely, you'll see a small step in diameter on the rightmost end. That's to match the step inside the bore through the tool post. To fit the original tool post, I drilled out the center hole to fit the new 12mm stud, and made a spacer, seen in front of the original tool post, to make up the difference between the height of the original post and the new tool post. The original tool post handle and nut was drilled and tapped to match the new tool post stud too. Done at last.

The second photo shows the new tool post mounted on the lathe. It's incredibly rigid. The weakest link now between the ways and the cutting edge of the tool bit is the compound slide. I believe it's because of the slide gib and the way the gib screws are designed and installed. It's a real mickey mouse arrangement, and will be the next thing I address as far as lathe modifications go. Also in the second photo is the original tool post, with the new spacer on top as it would be if the post were installed.


Anonymous said...

It is extremely interesting for me to read that article. Thanx for it. I like such themes and anything that is connected to this matter. I would like to read more on that blog soon.

Anonymous said...

Actually,good post. thx

Fred Becker said...

I have a similar lathe and had my doubts how to fit a quick change tool post. Thanks for showing this.

Smitty said...

You're welcome Fred. I checked in on your blog. How about a photo of your tool post installation when it's finished?