Presto 8dg overhead only hand cranks?

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sameal
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Presto 8dg overhead only hand cranks?

Post: # 47914Unread post sameal
Tue Sep 26, 2017 8:10 am

Hi everybody!

So i got the l.p.i. motor mounted and moving the shaft from the overhead into the lathe cabinet. But the worm gear doesn't move the overhead carriage.

If i use the hand crank, it works. Inbetween the handcrank and the overhead is another locking collar that moves with the l.p.i. motor setup.

What am i doing wrong?


( BIG thanks to SOULBEAR for all his help on the motor assembly)
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rsimms3
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Re: Presto 8dg overhead only hand cranks?

Post: # 47915Unread post rsimms3
Tue Sep 26, 2017 10:38 am

Ask Bryan, I think he had a similar issue or knows about it. I think it has something to do with switching between O/I and I/O cutting direction.

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EpicenterBryan
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Re: Presto 8dg overhead only hand cranks?

Post: # 47916Unread post EpicenterBryan
Tue Sep 26, 2017 12:37 pm

You might want to play with the collar on the right side of the lead screw.
Yours is set right now for inside to out but might not actually be fully engaged.

For outside to inside it should be positioned like mine is in the photo below:
IMG_5779[1].JPG

Bryan
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sameal
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Re: Presto 8dg overhead only hand cranks?

Post: # 47917Unread post sameal
Tue Sep 26, 2017 12:52 pm

I played with that collar, but i couldn't get it to engage the motor in either position it seemed. Only the hand crank

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sameal
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Re: Presto 8dg overhead only hand cranks?

Post: # 47971Unread post sameal
Sat Sep 30, 2017 7:59 pm

I had to disassemble the overhead entirely. The three little locking levers inside the gear assembly had been stuck open from solidified grease. I cleaned it up the best i could.

How much grease is really needed in there? It was caked on, but after i cleaned it i only put on a medium coat. Nowhere near the dollops that were in there.

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symatic
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Re: Presto 8dg overhead only hand cranks?

Post: # 52348Unread post symatic
Wed Feb 13, 2019 8:50 am

on my 14b there was a gear that came a bit loose which prevented the drive shaft from engaging when i had this problem.

different gear system though i imagine....

love the motor mod, would love to see what you used... I'm currently speccing up some pulleys to control the pitch drive off the main driver shaft for the platter.

I want to move towards a totally separate motor though eventually

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symatic
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Re: Presto 8dg overhead only hand cranks?

Post: # 52352Unread post symatic
Wed Feb 13, 2019 10:46 am

sameal wrote:Hi everybody!

So i got the l.p.i. motor mounted and moving the shaft from the overhead into the lathe cabinet. But the worm gear doesn't move the overhead carriage.

If i use the hand crank, it works. Inbetween the handcrank and the overhead is another locking collar that moves with the l.p.i. motor setup.

What am i doing wrong?


( BIG thanks to SOULBEAR for all his help on the motor assembly)
another question for sameal - is that a picture of a stepper motor with a timing belt connecting to a v pulley on the presto's shaft? I'm just wondering how easy it is to connect a modern motor to the older mechanism....

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sameal
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Re: Presto 8dg overhead only hand cranks?

Post: # 52391Unread post sameal
Sat Feb 16, 2019 5:20 pm

symatic wrote:
sameal wrote:Hi everybody!

So i got the l.p.i. motor mounted and moving the shaft from the overhead into the lathe cabinet. But the worm gear doesn't move the overhead carriage.

If i use the hand crank, it works. Inbetween the handcrank and the overhead is another locking collar that moves with the l.p.i. motor setup.

What am i doing wrong?


( BIG thanks to SOULBEAR for all his help on the motor assembly)
another question for sameal - is that a picture of a stepper motor with a timing belt connecting to a v pulley on the presto's shaft? I'm just wondering how easy it is to connect a modern motor to the older mechanism....
I used a motor soulbear used on his build and some off the shelf pulleys. It's a toothed belt, not a v-belt.

I made a cage out of aluminum pieces i robbed from an old tube oscilliscope plug in module and shock mounted the assembly to the existing holes for the anvil adjustment plate.

I did zero math on gear ratio, or actual l.p.i. so that has to be looked at. It pushed a small webster head, but i think for larger heads it may not have enough umph. It seems on the pwm controller the only useful speeds are at the last quarter turn of the pot. So i need to look into this harder soon.

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symatic
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Re: Presto 8dg overhead only hand cranks?

Post: # 52395Unread post symatic
Mon Feb 18, 2019 7:03 am

Ah sorry I meant the actual pulley you have - theres a toothed belt i can see, and a toothed pulley on the stepper motor - but does that just connect to a non-toothed pulley on the lathe's drive shaft?

cheers, and well done for gettign it working - i just received V pulleys for my presto... i'm going the original route to start with then i'll upgrade to a more controlled method like yours

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sameal
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Re: Presto 8dg overhead only hand cranks?

Post: # 52397Unread post sameal
Mon Feb 18, 2019 7:46 am

Both are off the shelf toorhed pulleys from ebay.The one attached to the overhead i had too bore out the center a little bit to fit.

My pulleys disappeared before i got to the machine. I think the previous owner had it running on a seperate motor and hand dialed the l.p.i. but none of what he added came with it. So here i am.

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