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-   -   Holmes Taig mini lathe build (http://www.rccrawler.com/forum/tools-procedures/330432-holmes-taig-mini-lathe-build.html)

JohnRobHolmes 08-08-2011 07:14 PM

Holmes Taig mini lathe build
 
I need a live center type support on my little mini lathe, but it needs to be a collet or chuck type because of the part size. This lathe uses 1/2" shafts for the dead/ live centers, and I have a 3/8-24 threads I could use to mount tooling.

Any suggestions before I make a new tailstock with bearings?

JohnRobHolmes 08-08-2011 07:17 PM

This with a 1/2" shaft would be perfect, but I can't find such a product yet.

http://littlemachineshop.com/product...ProductID=2504

JohnRobHolmes 08-08-2011 08:18 PM

Looks like I have just a few options here.

1. make or adapt a new tailstock, either bearing supported or mt2 taper
2. Modify a rotating chuck spindle to be 1/2" shaft instead of mt2
3. Figure out a clever way to use a steady rest, but there really isn't room for that.

jason 08-08-2011 08:21 PM

http://www.harborfreight.com/1-2-hal...uck-42340.html

Like you posted, but cheaper.

Still isn't what you want though.

JohnRobHolmes 08-08-2011 08:38 PM

Good job Jason :lol:


Probably going to just make a new spindle for a rotating chuck if I can't find something on the shelf. My bigger lathe has a compound rest (top slide) so I can cut tapers.

tom@vp 08-08-2011 09:43 PM

cant say ive even seen a chuck that could be used as a spinning live enter, the side load would make the chuck loosen off the taper that holds the chuck on the mandrel, drill chucks are usually designed basically for only linear load in the drilling direction. but there are chucks that are built one peice that dont press onto a taper, usually on those bench top manual mills. but i have not seen them able to spin, not saying they dont exist, just never seen one.

is there a reason why a live center does not work for you ?

JohnRobHolmes 08-09-2011 07:06 AM

The shafts are very tiny and I can't get a good dimple on them, and I don't want to be dimpling them all if I don't have to as it would require an extra step in the process.

Good call on the side load of the chuck loosening off the taper. Maybe I could get a thread on chuck and just have it mounted to a live axle.

Or maybe I could modify a live center to have an inside taper instead of putting a dimple on the work?

JohnRobHolmes 08-09-2011 11:23 AM

Ok, talked to a machinist friend of mine for about 30 minutes about this and he had some great solutions. He is really a free thinker and an experienced machinist.

Easy one- Buy a new headstock and use it in place of the tailstock. Pretty cheap.

Flexible one- buy another cross slide and set it up like a steady rest. Big bonus on this one is the super fast setup and part changes.

Best one- Make a dedicated tailstock or center for the task with a bearing mounted collet system. Similar to the dual headstock method, but customizable for the best clearances.


I am leaning towards the dual headstock method for cost (time) and parts reasons, literally a bolt up affair. The cross slide idea would be really pimp, just a bit more involved and less rigid. I don't have time to make a custom tailstock for the purpose, or else I would consider it.


Any more suggestions, post em up! I haven't finalized the design yet, but I do have some great ideas now. Maybe one day I could actually call myself a machinist :lol:

JohnRobHolmes 08-09-2011 01:35 PM

Decision has been made, I'm using a second headstock. It will be the most precise and rigid method, and cost the least as well. Can't really complain about that!

Charlie-III 08-10-2011 06:45 AM

Hmmm....missed this thread yesterday (sucks traveling for work:roll:).

I have an idea on what you want to do, but I think your decision on what you are going to do is the best bet.8) I can't think of a better & cheaper way.

JohnRobHolmes 08-10-2011 09:25 AM

Post it anyway! Good ideas for later are always welcome.

Cave Dave 08-10-2011 10:14 AM

I'm not sure what you are trying to support but here's an idea that would be cheap and EZ. Take a "dead " center and face it off and bore it to fit a bearing with the I.D. of the shaft you need to support.

semnmrc 08-10-2011 10:19 AM

I just saw this post also.

Sometimes thats the fun in machining and fabrication, problem solving! Sounds like you have a good idea.
Post up some pics of it when you're done, I always like to see how things work!

tom@vp 08-10-2011 10:33 AM

i dont know if you have seen this idea, but there are live centers with cup point tips such as this, royal is a premium brand but you get the idea

http://www1.mscdirect.com/cgi/NNSRIT...-SearchResults

this would hold onto the outside of the shaft with out needing a center drill hole in your part, we have use these with good success

tom@vp 08-10-2011 10:39 AM

here is a frugal model

http://cgi.ebay.com/SET-1MT-LIVE-CEN...item20bbb8e8c2

JohnRobHolmes 08-10-2011 11:00 AM

The cup point and bearing mount were options I had certainly considered. The only fault of the bearing is the need for many tools for different shafts.

I will probably make some cup points for future use. Seems like a good tool to have around. My one concern is whether it would center properly on shafts with keyways and flats.


Great suggestions!

tom@vp 08-10-2011 11:05 AM

you can also make a sleeve that slides on your part, and it has a live center point to locate the part.

just depends if you need to work on that area where the sleeve is

JohnRobHolmes 08-10-2011 11:16 AM

All kinds of trickery!

I will post up when the parts are in and I get the machine built. Seems that holding the parts to machine is more work than actually machining the parts.

Cave Dave 08-10-2011 11:39 AM

Work holding is often more chalenging than actualy cutting the material.

EddieO 08-10-2011 06:07 PM

Are you try to hold an armature or something else? I might have a way to hold it if its an armature.....but I am not as fluent in all the machining stuff...

Later EddieO


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