sliding head machine-guidebush type and guidebush less type

hi, we are looking at a new machine for which the manufacturer suggest to go in for guidebush less type sliding head machine. Can anyone give
their experience on using this type of machine on the advantages and disadvantages of having this type of machine over the guidebush type sliding head machine. Lawrence
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wrote:

Shorter bar ends. Less run-out - *IF* you're turning the OD. Don't have to buy guide bushings:-)
Just keep in mind that the length of your parts will be limited by the barstock diameter.
We sometimes run the cam operated Swiss (sliding head) without guide bushings. On these machines you can remove the guide bushing holder and slide the head up into the tool tree. Works great for profiled material (hex, square), and short parts. Wind up with little 2-3" bar ends, instead of 6-8" bar ends.
Star used to have what they called a 'Chuck Work' option. It was a spindle nose extension that fit up into the tool tree (after removing the guide bushing holder).
A guide bushing-less machine has it's place, but if you plan to run parts that exceed the length-to-diameter ratio of the barstock, you won't be happy with it. The only way to make longer parts is to do multiple chucking's, and then you'll run into concentricity problems.
Matt
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wrote:

Matt,
Tsugami has models that can convert from guide bushing to bushing less and back so you can do longer pieces if necessary. Not sure about other brands. Maybe Dan Murphy will followup and tell you more.
Another advantage of running without the guide bushing is that you don't need ground stock. But as Matt Stawicki said your length to diameter ratio is limited
VFP
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If your parts are over 3x diameter to length ratio then the guide bushing is the best option. For shorter parts running without the guide bushing will give you better roundness and runout when using cold drawn stock.
Tsugami machines can be switched back and forth. Machines like the Ganesh can only be run without, Star and Citizen machines currently can only be run with the bushing.
--

Dan

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Apparently you've get to spec it one way or the other, short sighted I think, but then again at the price range I think there talking about you could almost afford to buy both!

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