Quick change tool post compatibility

[Dabbler]

Normally the XL tool holders have the extra 1/8" milled out of the bottom of the tool holder. So a 5/8 tool in an XL tool holder should be close to the same height as a 1/2" tool in a normal tool holder.

Why the difference? the XL tool holders are far less rigid due to the thinner bottom. You can make a 5/8 tool work, but only for light cuts. in heavy cuts, you get bad surface finish and resonance. So if you have cheap or free 5/8 tools, they are a godsend. Otherwise, just kit up for the smaller tools.

 

[Thriller]

Why would anyone buy the 250-101 if the 250-102 is more versatile? Does the tiny groove take out a bit of the ridigity?

 

[Dabbler]

On the contrary, that little groove is OK for holding a small boring bar making light cuts. It's more of a jury rig, and there are holders that firmly grasp the boring bar, and so do a better job.... - so the goove one is mostly innecessary, but good in a pinch for a small bar, I have 2 in AXA and 2 in BXA, but I seldom use them for boring bars. I have them 'just in cases'...

 

[ttabbal]

One thing to keep in mind with multi-purpose tools like the 250-102 is that they tend to be alright for a few things, but not the best at anything. Look at some of the discussions about combo machines like the lathe+mill machines out there. They always have drawbacks. That isn't to say they are useless, just that you need to be aware of the possible issues. In this case, it's not a big deal. You can hold small boring bars, if you lack a better way to do it. It won't work as well as a dedicated holder, but it does work and I have done it. It seems like it would be a bit less rigid for normal lathe tools, but I've never seen a problem with that.

I'm building some holders, and not bothering with trying to find a way to groove them. I'll probably try building a dedicated boring bar holder though.

 

[RJSakowski]

OK great. So this is what I have learned so far. The 250-102 is different because it has the groove. I found you can also get a 250-102xl that will take a 5/8" instead of a 1/2". Now why would anyone buy a 250-101 if they had the option to buy the 250-102?

1. I believe the 102 is more expensive.
2. The floor of the slot sits higher, at least for some manufacturers, Shars included, which will prevent using 1/2" tooling on some lathes.
3. If using smaller tool bits, (1/8", 3/16", 1/4", &5/16", you may not be able to straddle the groove to properly tighten the bit.

If you are planning on routinely using a number of different boring configurations, you might want to have several 102 holders. On the other hand, if most of your work is with various turning and facing tools, it may be more advantageous to use the 101 tool holders

 

[RJSakowski]

On another note, I use the carbide boring bars from the boring tool for my mill for boring on the lathe. I found that the set screws on the tool holder dug into the shank of the boring tool, making it difficult to use in the boring head.

To avoid this, I made a saddle which fits between the boring bar shank and the set screws. I had to deepen the slot of the tool holder to allow centering the boring bar in the groove on the floor of the tool holder. I used a piece of square stock, centering it in my four jaw and boring a 1/2" hole and then splitting the stock. Alternatively, a hole could be bored in a bar and the outside squared on a mill.