PDA

View Full Version : My tool post version.



steve herman
03-05-2015, 02:11 AM
http://i784.photobucket.com/albums/yy126/steveherman/005_4.jpg (http://s784.photobucket.com/user/steveherman/media/005_4.jpg.html)
http://i784.photobucket.com/albums/yy126/steveherman/006_4.jpg (http://s784.photobucket.com/user/steveherman/media/006_4.jpg.html)
http://i784.photobucket.com/albums/yy126/steveherman/009_4.jpg (http://s784.photobucket.com/user/steveherman/media/009_4.jpg.html)
http://i784.photobucket.com/albums/yy126/steveherman/007_4.jpg (http://s784.photobucket.com/user/steveherman/media/007_4.jpg.html)








Bought an old craftsman 12" lathe and it didn't have a tool post set up so I built this one thinking that if a 1/4" keyway and a set screw could hold a pulley on a shaft it could work for an adjustable tool post.

Steve

The Artful Bodger
03-05-2015, 03:44 AM
That is somewhat like a Norman tool post, it seems all you need is the jacking screw and you could do away with the shims..

http://www.toolsandmods.com/lathe/mini-lathe-qctp

boslab
03-05-2015, 04:37 AM
I have what some call a clog heel toolpost, ie 4 way, I need a new one, an aloris clone from the peoples republic of that place!, I'm finding in some cases to get near the job I have a bit of tool sticking out and as a result some deflection, noticeable when parting as I've destroyed a few parting tools as the work has climbed, I'm still learning after turning for best part of 45 years, I'm corrupted by using big machines in work fairly regularly with everything 10 times bigger so it wasn't an issue, on a relatively small 12" swing I'm seeing different problems, tool deflection due to an as yet un diagnosed problem.
Your toolpost looks nice, well made, I'm sure you won't have any of the problems I get, I have to say you've done a nice job, well done.
I have a predisposition to heavy cuts, tips on tools in work liked it so you got used to it, not so at home, mind tips on a small machine with lighter cuts don't last as long as tips that got a thrashing!, another useful lesson.
Keep up the good work
Mark

vpt
03-05-2015, 08:35 AM
I agree with the jack screw to get rid of the shims.

Some aren't but I am a fan of having a handle on the "lock down nut" as well for quick turning of tool post adjustments.

See at 4:30 in my video here of a tool change and angle adjustment. https://www.youtube.com/watch?v=2wY3AbB1VLM

dian
03-05-2015, 09:32 AM
did you really measure the piece while the lathe was running?

oh, no, you marked the lenght, right?

steve herman
03-05-2015, 01:19 PM
There is a jacking screw under the yellow hex wrench, 3/8 16, that's the purpose for locking and unlocking the keyway so the tool holder can move up and down, the shims are only to place the small tool closer to the set screws. I should have made a better shot of that area.

vpt
03-05-2015, 05:30 PM
did you really measure the piece while the lathe was running?

oh, no, you marked the lenght, right?

Yes I was marking out .700" :D

No I don't leave the key in the chuck either, I was moving along a little quicker for the video. Any time I make a video I always feel the need to sort of hurry so the video isn't slow and boring.

PStechPaul
03-05-2015, 07:09 PM
Safety alert! In addition to above: ring on finger, long sleeves, incorrect file holding! Nah, just being picky, but important for beginners who should know the usual safety precautions. It's really a lot better to take short clips of each operation or edit out much of the repetive stuff for brevity. This should be a one minute video.

vpt
03-05-2015, 08:09 PM
Safety alert! In addition to above: ring on finger, long sleeves, incorrect file holding! Nah, just being picky, but important for beginners who should know the usual safety precautions. It's really a lot better to take short clips of each operation or edit out much of the repetive stuff for brevity. This should be a one minute video.



I feel more comfortable holding the file that way for some reason. :)

I wish I had some sort of video editing software and knew how to use it. Most videos people put together now days is quite amazing to me. I am lucky I know enough to get it from the camera to the internet.

dian
03-06-2015, 01:09 PM
long sleeves? do you work naked in the winter?. i mean, i have 11c in the shop now and a lot of people probably have less. i put on a winter jacket. the "long sleeve" stuff is stupid. you have to know, what your arms are doing. of course i shut off the machine, before i reach in there.

Paul Alciatore
03-06-2015, 02:29 PM
Looks like a nice tool post and I think the round post is a very solid design, far better than any dovetail, with it's limited contact areas, can ever be. But the big problem with the round post is repeatability. Of course, the first aim of a Quick Change Tool Post is the quick change feature. Your post does have that feature, especially with the adjustable handle locking screw.

But the problem with the round post is repeatability. Even with a keyway, the position of the tool tip will not be the same if you take it off and replace it. So, if you are making several identical parts, you can not count on the tool position being the same. The X-Y position may be the same, but the keyway will always have some play so the tool holder can rotate to different positions.

Another problem with a round post with a single, radial screw to lock it is that this produces a two point contact on that round post, one at the screw and the other at the 180 degree opposite point. This is not the solidest design. There will be some flexing, some distortion of the holder to make it conform to the post, but the problem is still there and the full potential of the round column for stiffness is not realized.

My solution to this was to employ a flat on the side of the round post and a holder which is effectively a split, round opening. A flat on the holder matches the flat on the post for positive, repeatable indexing. The tool tip returns to the same position every time that it is removed and remounted. So you can use the same dial numbers on successive parts.

http://img.photobucket.com/albums/v55/EPAIII/QConSBLathe.jpg (http://smg.photobucket.com/user/EPAIII/media/QConSBLathe.jpg.html)

But this design has another big advantage. When the holder is tightened on the post, it contracts to a full 360 degree contact. There is metal to metal contact between the post and the holder all the way around, not just at the front and back. Thus the two effectively become one hunk of metal. There is far less potential for any movement or vibration while cutting.

Although it is a bit hard to see because it is recesed, my design also does have the vertical positioning screw. It is located on the opposite side of the post from the flat. You can see it in this view.

http://img.photobucket.com/albums/v55/EPAIII/BytailStock.jpg (http://smg.photobucket.com/user/EPAIII/media/BytailStock.jpg.html)

This screw is locked with some fishing line in the threads and that seems to work quite well. There is no movement after adjustment from tightening a lock nut.

It rests on the flat base of the post. You can see the parts here.

http://img.photobucket.com/albums/v55/EPAIII/Disassembled.jpg (http://smg.photobucket.com/user/EPAIII/media/Disassembled.jpg.html)

The article:

https://groups.yahoo.com/neo/groups/MachiningTips/files/Lathe%20Accessories/

steve herman
03-06-2015, 07:27 PM
Your design is great and it is the one that got we thinking round tool post. the round shaft came out of my scrap box with a keyway all ready cut in it. if I would have made it from scratch I would have made a much larger round diameter. your design is the best I've seen without dovetails but still involves a lot of work which I was trying to avoid. I wasn't sure it would even work so I went for it and was surprised how well it does worked. Thank you for your input.

Steve

martik
03-06-2015, 07:30 PM
Did you try it without the keyway? That way you could rotate the toolholder without having to loosen the post.

steve herman
03-06-2015, 07:37 PM
That's a good thought, but on such a small dia. it probable won't hold. The key way is what I thought was the key to the design. Too many keys???

dalee100
03-06-2015, 08:48 PM
Hi,

I've been using a more "classic" version of the round Norman tool post for a few years now. Very solid, fast, and easy to make. Mine has a 1" diameter post and has never moved under .100" roughing cuts. But mine uses a pinch bolt to squeeze the tool holder tight to the post.

The only thing I don't really care for is the lack of indexing like a square dovetail post can provide. I always find it a pain in the backside to setup a cut off tool or threading tool. So I'm making a dovetail style now.

Dalee