What lathe attachment do I need?

[Aaron_W]

Aaron, it just takes much more time to set up your steady rest than gripping in your 3-jaw and going for it. all your are doing is reducing the 'whipping effect by using a plug. I think I've needed 3 or 4 plugs in 38 years, and they each took about 5 minutes to make.

I definitely can see the advantage for multiple parts, but for just 1 or 2, I was thinking it would be easier than making a new rest for the other end.

That is why I'm here though, to learn from those who have done it vs just a theory of how things work.

 

[kd4gij]

The lathe is 20x80 gap bed with a 4" bore. The steel table behind it is 8ft long with adjustable stands with V blocks lined with Delrin and kept coated with way oil. Once every thing is lined up and level it gets tested at low RPM . Machining is done at 300rpm and then polished at 500rpm.

 

[tjb]

I definitely can see the advantage for multiple parts, but for just 1 or 2, I was thinking it would be easier than making a new rest for the other end.

That is why I'm here though, to learn from those who have done it vs just a theory of how things work.

That's a good point, Aaron. However, in my experience, once you've done 1 or 2, chances are pretty good that you'll do 1 or 2 more some time in the future. That makes projects for the spider or the plugs attain a little more desirable economies of scale. Not to mention the invaluable practice gained from milling something out of leftover scrap metal or plastic. I find that every time I fabricate a little gizmo of some sort suggested on one of these threads, one of two things happens: Either I butcher a piece of scrap that I probably would have thrown away otherwise; or I end up with a functional do-dad that periodically comes into use on a subsequent project. In either event, I gain some much needed practice on something that just might have some useful application if I get it right. A win-win.

Regards,
Terry

 

[tjb]

The lathe is 20x80 gap bed with a 4" bore. The steel table behind it is 8ft long with adjustable stands with V blocks lined with Delrin and kept coated with way oil. Once every thing is lined up and level it gets tested at low RPM . Machining is done at 300rpm and then polished at 500rpm.

2" diameter; 14' long: If I did the math correctly, that thing weighs right at 150 pounds. Doubt if anybody would be using it for pole vaulting.

Regards,
Terry

 

[kd4gij]

The shaft is aqualoy 19 stainless steel. A little more than 150lb.

 

[RWanke]

2" boat shaft 14ft long.

View attachment 270392

That's a long shaft for 2". What kinda boat?

 

[kd4gij]

I never see the boats. Shafts get dropped off at my shop.

 

[P. Waller]

I never see the boats. Shafts get dropped off at my shop.

Nice setup.
I often use a back rest on a smaller lathe that has a 4 screw bearing chuck that slides along the frame. It is limited to 12 Ft. lengths or so because someone put shelving in the way (-:



We have a large W&S turret lathe with a similar setup as below but it has a hydraulic cylinder that will advance the stock along the frame when unchucked, this is very handy for moving long heavy bars.

 

[tjb]

Okay, here's the latest. I completed the lathe spider this afternoon - in an un-air conditioned shop, thermometer reading 93, humidity reading 98, and heat index reading 108. Lovely conditions. Here's a short pictorial progression with commentary along the way.

The train wreck: This is what happened a few weeks ago with 1/2" stock. The bend occurred about a foot from the outboard.

The lathe spider before drilling and tapping, along side the cut-off from the scrap piece I used and stand-alone.



Several shots (in no particular order) of the set up to drill the four holes for set screws. First, I horizontally mounted and indicated the rotary table; then mounted and indicated the chuck on the rotary table; then turned the assembly vertical and indicated to center; finally drilled the holes at 0, 90, 180 and 270 degrees.





Lathe spider with set screws (they're way too short but all I had). Will order longer ones tomorrow.


Mounted with a piece of 1" stock.


Thanks to all for your sage advice.

Regards,
Terry

 

[BaronJ]

Hi Guys,

A spider is fine for relatively short lengths of material protruding from the rear of the spindle. You can get away with having more protruding with thicker, greater diameters. In any event it is still dangerous practice.

The real cure to the problem is to use a tube secured on stands, so that the rod spins inside the tube and then it cannot bend and whip to cause damage and injury. The use of a spider is intended to stop quite small diameters becoming bent in relatively large lathe bores.

The use of tubes is very common on production machinery where long lengths of relatively small diameter materials are used. Once you get to a couple of inches "V" stands can be used, but even then if the material has a bend in it, or the risk of being bent a tube is still used.