The Shop > Tools
A Tangential Toolholder for the Sherline
bogstandard:
Bernd,
It always used to be recognised that the tool should be set a few thou low, but nowadays, with harder materials for both jobs and tooling the general concensus seems to be to set exactly on centre height.
For very heavy cutting, especially parting off at high speed and power, I personally set the tools a few thou high, to allow for downwards tool deflection. But you should never set tools high for normal machining, as the tool will 'rub' rather than cut. Set too low and the tool can be 'grabbed' and pushed under the job.
Instead of using a rule for setting height, just get a plain bit of strip, that will get over the graduations problems.
Hope this helps.
John
Bernd:
Thanks John.
If you look close at that last pic you'll see I used a piece of .020" (.5mm) feeler stock. Worked great.
Tried turning a piece of brass. Got a poor finish on that too. Time for investigating to see if I made the tool right.
Well tomorrow it's off to Cabin Fever and I'm hoping to see the boss there (Eric).
Bernd
bogstandard:
Bernd,
As with most HSS tooling, if you can get away with a very small tip radius, then a quick swipe across the nose with a stone works wonders. I use an Arkansas stone.
C-o-C attached
John
Bernd:
John,
I sharpened the tool again and gave it a couple of swipes to put a small radius on the tip. Then I put a sharp pointy tool in the chuck and set the hieght. I also turned the tool holder clockwise a few degrees to give more side clearence. It's supposed to be set square with the cross slide. I then took a small cut on the piece of brass in the picture. I then took a heavier cut also and different speeds. Finish is much better. I think both the radius and the larger clearence did the trick.
The picture below shows the piece of brass I used for the test. It shows the holder turned counter clockwise from square to the corss slide for facing. As you can see the tool is set a couple of thou low. It left a small nib in the center.
So adding more clearence and a radius seemed to work. As you can see I have some clearence issues with the tool clamp. It'll get in the way when facing larger diameters.
I'm going to leave the tool project as is for now. However I will post on how I cut the angles in the milling machine.
Hopefully I'll either have the pics posted tonight or tomorrow.
Bernd
Bernd:
Here's a quick look at how I machined several pieces of aluminum to make the tangential tool holders. A version if it was written up in "The Home Shop Machinist" Jan/Feb 2009 issue. I figure there had to be a better way to mill the tool block than what the writer had shown. He made his on a Sherline. I made mine on a Grizzly Mini-Mill or X2 style milling machine. I also have a Sherline lathe/mill combo.
I'm not going into a lengthy description or give dimensions. It was a tool holder I always wanted to try, plus I wanted to see if I could use less steps to accomplish the same thing. Weather I did or not is still in the air. The proof being in the fact that I have to turn the holder clockwise or counter clockwise from square to the cross slide table. You are supposed to be able to both face and turn without having to move the holder. Not true in my case. It does cut well though.
First pic is of the vise setup. Turned 12 degrees clockwise from square.
The two blocks of aluminum. 1.5" square by about 2" long.
The first of many cuts.
One side completed.
Both parts have the first side cut at 12 degree angle.
With the vise still at 12 degree the parts are clamped on there side that was cut earlier.
The second side finish milled.
Next will be the hole for the clamp and the slot for the tool bit. The one that's completed was my prototype and has a 1/4" slot for that size tool bit. The other two will be for a 3/16" and 1/8" HSS tool bit.
A rough guestimate of where the tool clamp will be.
Disregard the dimension on the scale. Locating the hole, just approximate.
Hard tapping the hole 1/4"-20. I just tighten the drill chuck enough so that the tap won't break when it hits bottom. How do I do it? Its just a sense of touch and some guts. <grin>
Milling the 3/16" tool slot.
Checking fit of the tool bit. That's about as deep as you'd want to go.
Both slots cut. Notice that when the holder is laid down in it's cutting position that the tool will be slanted 12 degree away from the center line.
All three lined up. 1/4" left, 1/8" middle, and 3/16" right.
The tool needs to be about .560" high or thick. So I'm using the prototype to scribe a line on the other two.
A quick trip through the band saw. I use a 6 tooth per inch raker tooth. Cut's like butter. Then a quick trip through the mill to clean up the saw cut.
And here is the tool on try out cutting. The blade holder is nothing more than a piece of steel with a hole in it and one surface mill so when clamped it will be parallel with the tool.
That's it for now. I'm not going to go and develop this much beyond some clearances so I can face larger diameter pieces. I want to concentrate on building the coke bottle engine I've started. This was an experiment to see if I could do the job in less set ups than the author used in his article. I think I succeeded. I'm just not sure I have some of the angles right. I did this to see if I could make a tool to better turn the bronze material of the coke bottle engine. I think it would but will resort back to the regular tool post that came with the Sherline for now. Perhaps when I finish the engine I'll resume on the tangential tool holder.
Questions?
Regards,
Bernd
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