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Lathe Spindle spider

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Ski

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#1
I need to make one to fit the left side of a South Bend 13" and wondering if we could get some pics posted of these ? I have a good idea how I want to make one but thought I'd see what others have done. I need to shorten a long screw and the only way it is going to happen is run it through the headstock. Ski
 

Kevin45

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#4
I need to make one to fit the left side of a South Bend 13" and wondering if we could get some pics posted of these ? I have a good idea how I want to make one but thought I'd see what others have done. I need to shorten a long screw and the only way it is going to happen is run it through the headstock. Ski
One of the easiest ways to shorten a long screw is to take a drill bushing the size of the outside diameter of the screw threads, and take a dremel and split the bushing. Put the screw through and chuck it up in either a collet head or a three jaw chuck. Or if you don't have a drill bushing, take a piece of aluminum or steel that is larger diameter than the head of the screw, drill a hole through that is the clearance size for the screw, then split it with a Dremel or a hacksaw. You now have a small collet to hold any size of screw you make it for. If you have a quantity of screws to cut down, make the collet the length that you need, and tough off of it each time. Fast and easy.
 

Ski

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#5
kevin, The screw I have to shorten is the x axis screw for a Lagun verticle mill. It is big. I got a screw for a 56" table for cheap that is new. My mill has a 42" table. Ski
 

Kevin45

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#6
kevin, The screw I have to shorten is the x axis screw for a Lagun verticle mill. It is big. I got a screw for a 56" table for cheap that is new. My mill has a 42" table. Ski
Yea.....forget the drill bushing then. LOL!!!! After rereading things, I don't know what I was thinking when I responded. Cutting something long, you want to make sure that it doesn't flop. Cut off what you can if you have a chopsaw. If you don't want to make a special adapter for the end of the headstock, a lot of times I would shove paper towels in the excess area to keep a rod or shaft from flopping around. If the shaft is excessively long, even though it is not a real safe idea in a shop atmosphere, take a piece of PVC tubing that will slip over the shaft or leadscrew, and have someone hole it fairly steady while you machine the other end which will be centered anyways in the chuck or collet.
 

Ski

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#7
I am working on a spider so I can adjust for TIR what hangs out left of the spindle. I am hoping that will do the trick. I plan on measuring and cutting just as you suggested with a chop saw. Them machining a nipple and bore and pinning them together. Ski
 

David M

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#8
IMG_2063.JPG

I am a little hesitant to post this, might bring new meaning to the word "crude". I had to turn the end of a piece of round stock down the other day and this is how I supported the end of it, not pretty but it did the job. For what you are doing it sounds like you are going to have quite a bit of screw hanging out past the end of the spindle even with a spider, maybe you should give some thought to some way to support your screw all the way at the end.

You can go ahead and copy this if you want...I wont mind.
 
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Ski

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#9
Get er done ! Was going for one that is little bit more purty though. This is actually doable in my shop though since my bench is to the left of the lathe. I'll save this idea for the extra extra long shaft job ! Ski
 

Ski

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#10
This is it in its infant stage. image.jpg
 

TTD

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#11
View attachment 95908

I am a little hesitant to post this, might bring new meaning to the word "crude". I had to turn the end of a piece of round stock down the other day and this is how I supported the end of it, not pretty but it did the job. For what you are doing it sounds like you are going to have quite a bit of screw hanging out past the end of the spindle even with a spider, maybe you should give some thought to some way to support your screw all the way at the end.

You can go ahead and copy this if you want...I wont mind.
Hey, how 'bout that...apparently we shop for our accessories at the same place!:D

I've used that (almost) exact same setup a couple times now. Like you said - it may look crude, but it does the job....but still not as crude as a bent bar smackin' you upside the head, or (in your case) sticking through the garage door! ;)
 

Andre

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#12
I built one for my SB 13", to turn a 7/16" 24" long airgun barrel; only to find out the barrel never reached that far back.....:(

It was a two diameter bushing, one to fit snugly inside the back of the spindle and a larger diameter to stop it from going in too far. It is split with a set screw, so it expands and locks in place. Four socket head cap screws get screwed into the exposed portion to support the work. I'm sure I will find a use for it someday.
 

David M

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Hey, how 'bout that...apparently we shop for our accessories at the same place!:D

I've used that (almost) exact same setup a couple times now. Like you said - it may look crude, but it does the job....but still not as crude as a bent bar smackin' you upside the head, or (in your case) sticking through the garage door! ;)
It is surprising how few people know that the Home Depot sells custom lathe tooling......

And, Amen on the head/garage door thing!!
 

AJB

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#15
Here is a picture of the spider I made. It was placed close to the headstock instead of outside of the gear cover so that it could be used with shorter rifle barrels (under 20" with a four jaw chuck).
image.jpg

It is threaded 7/16x20tpi and both the spider and the spindle are threaded. (I tapped the spider and spindle at the same time.) It uses brass tipped screws made from 1" long set screws.

In use, the gear cover is cracked open a bit to access the spider screws then fully closed during turning.
 

NightWing

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#17
I have read this thread several times and frankly, it has sent shivers up my spine. I am not standing in judgment of anyone or any process, but I have had first hand experience with rotating bars maiming or killing people. Plus, I have had a serious mishap on one of my own machines that cost a lot of money to repair.

Years ago, I was a field service engineer for a well known builder of multiple spindle automatic bar machines…screw machines if you would. These machines had 4, 6 or 8 spindles with a capacity from 9/16 to 6 inch stock, depending on the model of the machine and the number of spindles. After 10 years in the field, I was promoted to Product Service Manager and brought back to the plant. One of my responsibilities was to investigate any serious accidents on one of our machines anywhere in the country. I had a couple that I will never forget.

The first was in a factory in one of the southern states. They had a line of machines we had built. Most were 1 5/8” capacity with 8 spindles. These machines are usually equipped to run 12 foot bar stock. They have a stock reel that indexes with the spindle carrier, holding the 8 bars in line with their respective spindles. Each spindle has a collet closing mechanism and the machines run automatically, feeding stock, machining it and cutting a workpiece off every cycle. The stock reels are designed to swallow the entire bar length of 12 feet. Customers desiring to run longer stock would buy machines with longer stock tubes or retrofit what they already had. Some chose to do otherwise.

An operator had just loaded his machine with a fresh load of stock…stock that was too long and the bar ends were protruding out of each stock tube by a couple of feet. The man started his machine up and one of the bars started whipping and striking the other bars, causing them to bend and strike each other. Within a few seconds, one of the bars broke off and it went flying across the department, striking a female operator at another machine. It hit her in the head, fracturing her skull and killing her almost instantly. Once my company became aware of the accident, I was on the next plane out to investigate, take photographs and interview as many people as I could. The company where it happened had shut the area down tight after the woman’s body was removed. They didn’t touch anything, waiting for my arrival. It was a gruesome scene, with blood, pieces of hair and scalp and brains strewn about. I spent about 3 days there and returned with many pages of notes and over 100 photographs. All that information along with my report was forwarded to our corporate attorneys.

The next incident occurred in another southern state, near the Mexican border. That company had only a few old machines that were over 75 years old, but they were technically built by our prior owners. Over the years, my company had changed hands several times.

This accident was tragic as well. A young janitor was mopping the floor near the screw machines. It was a very hot day, so he had only his underwear on under his coveralls. One of the machines had rotating bar ends exposed, not much, but they were not covered by the stock tubes. He got too close to the machine and his coveralls were caught by the rotating bar. The machine indexed and his coveralls were ripped completely off, including his underwear…and his scrotum. A young 24 or so year old man, newly married, was maimed and would never be able to father a child. Some time later, I heard from the attorneys that the settlement was 7 figures.

Finally, after 18 years of working for a machine tool builder, I started my own screw machine shop. Eventually, as I grew, I bought a couple of new Mazak CNC lathes. Most work I did on them was in collets and I had a bar puller on the turret. I made urethane liners for the spindle for every stock size I ran. I saw-cut 12 foot stock into lengths that would be totally enclosed in the spindle. One day, I had an odd-ball length of 3/4 inch stock that stuck out maybe a foot. I thought I could get away with it.

I started the machine up and the spindle started to wind up to 6,000 rpm. Before I could hit the E-stop button, the machine started to shake and make horrible noise. Once it was shut down, I could see that the bar had bent 90 degrees and that piece broke off hitting the ceiling. The machine which weighed 7,000 pounds had actually moved a couple of inches. .

I was shaking with the thought of what could have happened. I unchucked the bar and removed it from the spindle. I opened up the covers over the rear of the machine and slowly jogged the spindle. I could see the chuck actuator was wobbling. Not good. I did some checks and found the spindle module had moved. It was time to call Mazak Service. They sent a service tech and he said the spindle was bent and couldn’t be repaired. The actuator was also damaged beyond repair. He undressed the machine and removed the spindle module, which he took back to Mazak Service Center. The machine was down for a couple of weeks. The cost of repair was over $8,000. My poor choice of allowing a bar to extend past the spindle was a frightening, expensive lesson. The worst part was, I knew better, but didn’t think it could happen to me.

I am going to make reference to this post in the Safety section. I believe there are lessons to be learned. Please, everyone be safe.
 

Ski

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#18
Safety is somethingI try to keep in the front. That is why I am making the spider attachment. I don't like pain. Ski
 

GarageGuy

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#19
I started the machine up and the spindle started to wind up to 6,000 rpm. Before I could hit the E-stop button, the machine started to shake and make horrible noise. Once it was shut down, I could see that the bar had bent 90 degrees and that piece broke off hitting the ceiling. The machine which weighed 7,000 pounds had actually moved a couple of inches.
I appreciate your experience, and would never discount proper safety... but 6000 RPM is not in the same order of magnitude as 400-750 RPM where a home machinist would cut or turn something like a lead screw. Just pointing out the difference. David M's Home Depot spider is still well within it's safe operating range at 400-750 RPM. Again... not saying ignore safety, just that there is a big difference between 400 RPM and 6000 RPM.

GG
 

LEEQ

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#20
A fellow could stick the lead screw through the four jaw and a steady rest with the portion to be machined sticking out past the steady. Dial it in nice, then add that high end Home Depot holder to the bench to keep the protruding screw end contained and running nicely. That being said, I will build a spider even though there could be work arounds.
 

NightWing

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#21
I gave three examples of how rotating stock can be deadly. Whether it is protruding too far from the spindle or running exposed, rotating stock is a hazard regardless of spindle speed.
 

kd4gij

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#22
Manuel mschines have exposed rotating mass always use exstream safty . When running longer stock eather out the back of the head stock suported or with a stady rest and or live center.ALWAYS check your setup at the lowest speed posible and fine tune the setup. Then work up to speed. I turned a 22ft long x 3 inc dia boat shaft today. But won't go into the setup here.
 

KBeitz

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#23
When I was just a kid I was working with an 8 foot 1" bar.
The bar bent and took out a whole row of shelving and corded tools.
It cut the shelves right down the middle and also cut some of the
tools in half. Was a good learning experience. No harm to the lathe.
 
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