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Lathe questions

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Lathe questions

Unread postAuthor: Alster370 » Wed Sep 14, 2011 2:09 pm

So, I finally got my lathe. Its a seig c0, and I know your probably going to say that the size will restrict me, but it wont as I don't need to turn anything big. :D As im quite new to high-tech machinery, (like lathes for example) I have a few questions regarding them:

1.) what depth of cut would I need for an o ring groove on a piston of 19mm?

2.) Am I ok to remove the tail stock so I can work with a longer work piece?

3.) I sometimes get a fairly nasty shock when I have the lathe running and my hand is touching the variable speed control knob, despite it being made of plastic, any thoughts?

Cheers :D
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Re: Lathe questions

Unread postAuthor: velocity3x » Wed Sep 14, 2011 2:17 pm

Alster370 wrote:1.) what depth of cut would I need for an o ring groove on a piston of 19mm?


This link contains design criteria for static and dynamic o-ring applications.
http://www.allorings.com/oring_groove_design.htm

2.) Am I ok to remove the tail stock so I can work with a longer work piece?


If a work piece is long enough to require removal of the tail stock, it's much to long to run unsupported.
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Re: Lathe questions

Unread postAuthor: jackssmirkingrevenge » Wed Sep 14, 2011 2:18 pm

After showing us all those quality second hand ones, how come you went for this?

Alster370 wrote:1.) what depth of cut would I need for an o ring groove on a piston of 19mm?


What's the o-ring inner and outer diameter?

What is the true diameter of the tube it will be riding in?

2.) Am I ok to remove the tail stock so I can work with a longer work piece?


As long as the piece is properly held, and you're working near to the chuck, it should be fine. Consider getting asteady rest though.

3.) I sometimes get a fairly nasty shock when I have the lathe running and my hand is touching the variable speed control knob, despite it being made of plastic, any thoughts?


Stop using it immediately and have it checked out by a competent electrician. It could be down to static buildup due to friction, but I wouldn't risk it.
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Unread postAuthor: Alster370 » Wed Sep 14, 2011 2:30 pm

tube inner diameter, is 19.5mm. Im also looking for what size o ring I would need, as I am unfamiliar with them and which size I should go with for a piston of this diameter. Any general rules to follow concerning this?

Ok, I think i will try without the tailstock and make a decision based on its balance and how heavy the work piece is. Also on how much the work piece is exceeding the maximum length with the tailstock.

Also as a sidenote, this electrocution is not while im cutting or grinding, just as the machine is spinning the work piece.
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Unread postAuthor: jackssmirkingrevenge » Wed Sep 14, 2011 2:43 pm

Alster370 wrote:tube inner diameter, is 19.5mm. Im also looking for what size o ring I would need, as I am unfamiliar with them and which size I should go with for a piston of this diameter. Any general rules to follow concerning this?


velocity's link is useful.

Coincidentally my latest fill righas a 19.5mm ID :)

Image

I used AS568A-113 rings fromthis set.

Ok, I think i will try without the tailstock and make a decision based on its balance and how heavy the work piece is. Also on how much the work piece is exceeding the maximum length with the tailstock.


Careful with long thin material, it can whip around and hurt you.

Also as a sidenote, this electrocution is not while im cutting or grinding, just as the machine is spinning the work piece.


Is the drive belt rubbing against the body?
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Unread postAuthor: Alster370 » Wed Sep 14, 2011 2:49 pm

Well its more of an estimate than an actual value, I still havent been able to get a reply for the ID of 22mm copper pipe from my supplier. :? So i just thought id buy 22mm round bar and trim it till its a good fit.


Is the drive belt rubbing against the body?

Il check in a minute, I can run the lathe with the cover off right?
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Unread postAuthor: jackssmirkingrevenge » Wed Sep 14, 2011 2:58 pm

Image

I suggest you get yourself some Delrin or UHMWPE for piston materials - easy to work with, low density and cheap :)
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Unread postAuthor: Alster370 » Wed Sep 14, 2011 3:35 pm

The belt had bits of rubber still attached to it where it had been cut, so Ive shaved those off and I don't get electrocuted any more! :D

Isn't delrin acetal? :P its quite expensive too :?. Il definitely get some aluminium barstock, soft, strong and surprisingly cheap :shock:
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Unread postAuthor: jackssmirkingrevenge » Wed Sep 14, 2011 4:11 pm

Alster370 wrote:The belt had bits of rubber still attached to it where it had been cut, so Ive shaved those off and I don't get electrocuted any more! :D


Told you so ;)

Isn't delrin acetal? :P its quite expensive too :?. Il definitely get some aluminium barstock, soft, strong and surprisingly cheap :shock:


"soft" and "strong" eh :roll:

In my limited experience I've discovered that I much prefer brass.

Yes, Delrin is acetal, the prices I've found are pretty reasonable.
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Unread postAuthor: DYI » Wed Sep 14, 2011 4:22 pm

soft, strong


Sorry Alster, the world doesn't work like that :P
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Unread postAuthor: Fnord » Wed Sep 14, 2011 6:07 pm

Sorry Alster, the world doesn't work like that


Ha! Student of "advanced science" my butt.
You haven't seen the ETG prototype I'm making from Cubic-Bubblegum Nitride.
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Unread postAuthor: velocity3x » Wed Sep 14, 2011 11:03 pm

Alster370 wrote: Im also looking for what size o ring I would need, as I am unfamiliar with them and which size I should go with for a piston of this diameter. Any general rules to follow concerning this?


Did you totally disregard the link I posted for you? All the necessary info is there.

Select your o-ring(s) to fit the bore size....not piston size.
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