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View Full Version : can a car scissor jack for a Z axis?



NickLatech
01-14-2005, 09:03 AM
I can get an XY from

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=25297&item=3843404692&rd=1&ssPageName=WD1V

and the stepper / driver from

http://www.hobbycnc.com/cncpackages/4aupcpkg/4aupcpkg.htm

That leaves my Z axis not finished.

I was wonder if anyone has uses a car scissor jack for a Z axis?

if anyone else has any cheap ideas, please let me know... I'm brain storming.

Nick

JavaDog
01-14-2005, 10:49 AM
There is a lot of play/backlash in a scissor jack.

However, I wonder if the threaded-rod from a scissor jack, with a custom delrin/uhmw nut, would work?

ViperTX
01-14-2005, 11:01 AM
NickLaTech,

PITS on Ebay has a larger table for about the same price. The cast iron is good the leadscrews are cheap.

For headache less performance http://www.cnconabudget.com has an instant z-axis for around $200.

Ben Olson
01-15-2005, 01:28 AM
japanese car jacks are a good source for fairly reasonable acme screws

if you only need a very short ball screw a manual steering box has one in it ( precision ground threads too :) )

Pythagoras
01-15-2005, 02:03 AM
The problem with scissor jacks are that you get more lift at the start of the winding and less at the end. The lift is not proportional the amount of turns along the thread. You would not be able to get your drivers to compensate for the variing proportions. Do you understand what I mean ?

jcc3inc
01-15-2005, 10:50 AM
Dear Sir:

As a good source of acme screws, consider Green Bay Manufacturing at 920-793-2411. They are in Two Rivers Wisconsin and make acme threads from .375-12 to 2.0"-4 so there is lots of range!

Regards,
Jack C.

Hobbiest
01-15-2005, 02:05 PM
here is a pretty good unit.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=3866350549&ssPageName=STRK:MESE:IT
Only has about 3.5 inches of travel, and you would need to put a couple of slides on it, but other than that it is already built. Figuring out how to mount it to your machine could be tricky. Might have to have the router mounted sideways.