Bridgeport tooling

[Bernd]

In my build thread for the Four Truck Shay I mentioned making some tooling. Well here's what it involves.

My Bridgeport has a Kwik Change spindle. The picture below shows the tooling. The tool holder is on the left. On the right is a blank that I will attempt to turn into a tool holder for a boring head (yet to be made).



In order to mill the ears on the blank I will need to use my rotary table. Problem is the slots in the table will not take the T nuts that go into the Bridgeport table. I had made some T nuts but had threaded them for 5/16-24 for some reason or other. Now I need to fasten my small three jaw chuck down. So I needed some longer threaded rod. None to be had at the hardware store. What to do? Well I'll use the nuts I made and make some extentions. This is what I came up with. They're not done yet. Still need to drill and tap the top of the rods.



So what am I leading up to? Well I made a tool holder that will hold a 5/8" Dia. end mill since I don't have a collet bigger than 1/2" for the Kwik Change tooling. I made an adapter to fit into the 1/2" tool holder. I started to use the mill and tool holder to start milling the truck journal boxes. I had a samll "crash" didn't hurt the mill or part but bent the holder so that it wobbles. You won't see it in the picture, it's that small of a bend.



As you can see that quite a bit of the tooling sticks out from the holder.



I determined the reason it bent was that the 1/2" part was to short for the collet. The collet must had let go casung the mill to twist. The picture below shows the anatomy of the holder.



So as soon as the finace dept. finds a couple of extra bucks laying around I will purchase another piece of 3" leaded  (12L11?) I'm going to make a solid tool tool holder for the Kwik Change spindle. Until then the Shay has to wait.

Bernd

[Pete.]

Quite a lot of over-hang for a 1/2" arbor. I make similar holders but since I use R8 collets that sit almost flush in the spindle I can machine an undercut so that the holder bears on the spindle end when the collet pulls it in. I also use a 3/4" collet to hold custom adapters which is obviously stronger.

[doubleboost]

That rotary table looks the same as mine 
Japanees oil filled job
John

[Bernd]

John,

Ya, that's a China deal. All meteric. But it serves it's perpose nicely.

I cut the ears on the blank after finishing the extensions. Trued up the chuck and had at it with a long 1/2" endmill. Cut great.



Getting close. All I need to do is cut the taper and trim up the ears or tabs if you will.



Here's a few pics of a commercial one. This can be gotten from a second hand sellers for $55. By the way this is a holder for a 5/8" dia. end mill.









This holder will ultimatley go for the boring head that's written up in the book workshop practice 35 the milling book. All I need is another hunk of 3" 12L14 to make the 5/8" holder.

Bernd

[udimet]

Bernd,
                 Just an suggestion, you would be far better off if you were to make the endmill holder from a stronger grade of steel such as EN 24T which is known in America by it's AISI No- 4340.
 The biggest problem when making these type of holders from softer steels especially leaded steels is the tendency for the holder to "Bell mouth" which simply means that due to the cutting forces they mouth of the holder can eventually look like a bell  which causes all sorts of trouble but maybe for a 1off  to be used once then thrown away it would be ok, but really long term you would be better off with 4340.
                                                                                                                Regards,
                                                                                                              Udimet.

[Bernd]

Udimet,

Thanks for that suggestion. I will take your advise under consideration.

Well I've got my first holder done and it fit in the spindle without falling out. Nice snug fit to. So I'm going to be making one for the 5/8" end mill probably using Udimet's suggestion of using 4340 steel.

Here's a pic of the finished taper and trimed up tabs.



Bernd

[Bernd]

 

Well I made a second holder. Not very successful. I believe I turned the taper to far for a good fit, plus I had taken to much off the ears to make a nice tight fit in the spindle.

Then I asked myself why do I want to use a 5/8" dia mill when a 1/2" mill will work just the same only it's 1/8" narrower. 

So as soon as I get some free time for model work I'll have a go at those castings again. 

Bernd