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Rebus
2nd Jan 2005, 10:38 AM
Greetings,

I was waiting for someone else to start the ball rolling but everyone must be on holidays.

I recently bought a 12" x 36" Herless lathe and have been practising by making up a master/slave chuck system and a tapping/threading guide for mounting on the tailstock.

While working on these things I have hit the usual problem of lost time and effort in changing from one tool to another. The answer is, of course, a quick change toolpost. Checking the Herless catalogue, I can have my very own for a mere $495.00 :eek: and that's with only 3 + 1 holders. :mad:

So, off to Google and search out plans for DIY quick change toolposts. A couple of hours later and a number of fundamental questions appear:


The Wedge: Is it best to have the Tail on the toolpost and the Pins on the toolholder, or vice versa, or doesn't matter ?

Locking Mechanism: I have seen examples where the toolholder is locked by:

A cam forcing out a pin which presses against a plate which in turn pushes the toolholder away from the body thereby locking the wedge. (refered to as a piston style)

Examples:
http://home.inter.net/mthomas/quick_change_tool_post.htm
http://homepage.ntlworld.com/v.ford/qctp.htm

A pin with a wedge shaped end which pulls one side of the toolholder against the toolpost.
Example:
http://www.metalwebnews.com/howto/toolpost/toolpost.html

A toolpost which has been split and is pulled closed to lock the toolholder.
Example:
http://homepage.ntlworld.com/v.ford/gtmake.htm


So, what is the best way ? Your thoughts/experiences are welcome.

Regards,

rodm
3rd Jan 2005, 01:35 AM
Hi Rebus
I have got the Herless AL-330A and have been casually looking at QCTP and found one on Ebay for about $300. It gets relisted every ten days so try this link
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&category=633&item=3863111834
It is worth having a look at his ebay shop as he carries a lot of lathe and milling gear and cheaper than H&F because he doen't have the overheads.
I can't help you with the design of a QCTP but I can point you to a couple of forums that will provide you with the info you require.
I did look at making my own but gave up on it because you will need a dovetail cutter and this costs about $150. From what I have read the dovetail cutter is fragile on the tips of the teeth and easy to break. As I sometimes are a bit heavy handed it could end up being a very expensive exercise. If you haven't got a mill you will need one of those too or a shaper.
Keep those chips flying. :)