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Grafting feedscrew (Q from a new guy)
Grafting feedscrew (Q from a new guy)
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Grafting feedscrew (Q from a new guy)
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04-28-2015, 11:20 PM
(04-28-2015, 09:20 PM)Pete O Wrote: Is crashing as much an issue with the crossfeed as with the longitudinal feed? The drive gear on the leadscrew of my lathe is a slip fit with a tapered pin, so the drive is only transmitted by the pin. However if I introduce a clearance fit into the middle of the crossfeed screw, as it is only supported at either end, I think it would cause problems with sagging in the middle (like me). Oops. I was thinking you were joining the leadscrew. The cross feed screw does not need a shear pin because it is driven by the leadscrew. Nevermind. Tom ![[Image: TomsTechLogo-Profile.png]](http://tomstechniques.com/wp-content/uploads/2013/11/TomsTechLogo-Profile.png)
04-28-2015, 11:56 PM
(04-28-2015, 05:58 PM)DaveH Wrote:(04-28-2015, 04:15 PM)EdK Wrote: I guess I misspoke. My lead screw is pinned but not with a shear pin. It's pinned with a 3/16" spring pin with a breaking strength of about 4100lbs. And then for poetic justice, some of us engineers have to build our own designs. One of the kids and I were making a cross country trip when he was about 3. Stopped at a dinner and got chatting with one of the locals, he asked what I did, told him I was an engineer, Charlie looks up at me and say's no your not, you don't drive a train.
Free advice is worth exactly what you payed for it.
Greg 
04-29-2015, 04:54 AM
04-29-2015, 07:17 AM
It seems to happen all the time, one part is replaced with another part just to save 0.5 cent with little or no thought.
I also thought we were talking about the main lead screw  I think I have lead screws on the brain  DaveH 
04-29-2015, 07:41 AM
Did somebody say "Logan"? The leadscrew gear on mine has a bunch of spring loaded detent balls between the gear and the hub. I left a board on top of the chip tray a while back and heard the gear let loose when the board caught the carriage. I don't remember the sound it made but it sure got my attention.
Mumble, grumble.. Can't turn a taper.. Wish I had your lathe. Both of mine turn tapers all by themselves. 
04-29-2015, 04:03 PM
It's called a Safety Gear. Unfortunately mine doesn't have one. It was an option that's no longer available and I haven't seen one on ebay (yet).
Logan 200, Index 40H Mill, Boyer-Shultz 612 Surface Grinder, HF 4x6 Bandsaw, a shear with no name, ...
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04-29-2015, 10:54 PM
(04-29-2015, 04:54 AM)EdK Wrote:(04-28-2015, 10:53 PM)Dr Stan Wrote: sounds like someone replaced the shear pin with a spring pin. Not too difficult to correct. Still does not sound right. The spring pins could have been installed by an error at the factory. IMHO I'd replace it with a very soft steel or even aluminum pin just to protect the more expensive parts of the lathe. 
04-29-2015, 11:33 PM
Mine has a spring pin too (lead screw to gearbox) from the factory. Bought the lathe new in the crate.
Willie
04-30-2015, 05:37 AM
(04-29-2015, 10:54 PM)Dr Stan Wrote: Still does not sound right. The spring pins could have been installed by an error at the factory. IMHO I'd replace it with a very soft steel or even aluminum pin just to protect the more expensive parts of the lathe. Not likely a factory error, more likely a design error. How would one go about figuring out the correct diameter and material to use to replace the spring pins with shear pins?  Ed |
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