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Grafting feedscrew (Q from a new guy) - Printable Version

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RE: Grafting feedscrew (Q from a new guy) - Dr Stan - 04-28-2015

(04-28-2015, 05:58 PM)DaveH Wrote: This will get me into a lot of trouble. Smile
Your lathe was designed by engineers made by machinists. Cool
Smiley-eatdrink004
DaveH

Yep, just when you think it's all blown over the anvil will drop.  Ouch


RE: Grafting feedscrew (Q from a new guy) - TomG - 04-28-2015

(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).
I'm not sure I have the confidence to produce a tapered fit, I'm only going to get one chance at this (unlike the threading of the new nut, thankfully) and don't want to risk destroying the driven section of the shaft.

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


RE: Grafting feedscrew (Q from a new guy) - f350ca - 04-28-2015

(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.  Yikes

Ed

This will get me into a lot of trouble. Smile
Your lathe was designed by engineers made by machinists. Cool
Smiley-eatdrink004
DaveH

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.


RE: Grafting feedscrew (Q from a new guy) - EdK - 04-29-2015

(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.

Nope, came right from the manufacturer that way.

Ed


RE: Grafting feedscrew (Q from a new guy) - DaveH - 04-29-2015

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 Bash  I think I have lead screws on the brain Bash 
Smiley-eatdrink004 
DaveH


RE: Grafting feedscrew (Q from a new guy) - Sunset Machine - 04-29-2015

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. Smile


RE: Grafting feedscrew (Q from a new guy) - Vinny - 04-29-2015

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).


RE: Grafting feedscrew (Q from a new guy) - Dr Stan - 04-29-2015

(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.

Nope, came right from the manufacturer that way.

Ed

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.


RE: Grafting feedscrew (Q from a new guy) - Highpower - 04-29-2015

Mine has a spring pin too (lead screw to gearbox) from the factory. Bought the lathe new in the crate.


RE: Grafting feedscrew (Q from a new guy) - EdK - 04-30-2015

(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? Chin

Ed