# How To Hold It?



## RVJimD (Apr 11, 2015)

I am trying to figure out how to hold this in the lathe.  What about putting a dowel pin in each jaw so the pins don't interfere with the spokes like the full jaw?  I need to put a shallow groove in the outside for the O ring.

I have tried to use a stub of delrin but the wheel slips on the arbor.  I guess I could make a 3/4" arbor and thread it?

But, has anyone done dowel pins in the jaws?  I would need to turn it real fast, just getting the holes drilled in the jaws all in the same place might be tough.

Jim


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## Cobra (Apr 11, 2015)

Could you make an expanding arbor for the centre?


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## Billh50 (Apr 11, 2015)

An expanding arbor would work. Another thing you could do is make an arbor with a backing large enough to put a pin toward the outside edge that would fit between the spokes and a cap to tighten the wheel. The pin would keep the wheel from slipping on the arbor.


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## toag (Apr 11, 2015)

If you have a 5ccollet nose you could use an expanding 5c collet.


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## RVJimD (Apr 11, 2015)

Expanding collet sounds good but I don't have a 5C.  The pin idea sounds very good!

Jim


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## toag (Apr 11, 2015)

I have some expanding arbors if you want to borrow one.  If you don't have 2 piece jaws I'd hate to see you drill into your jaws


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## RVJimD (Apr 11, 2015)

Ya, I did some more searching and instead of drilling the jaws it seems like making soft jaws would be better..  Although not a perfect solution  for this operation.


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## toag (Apr 11, 2015)

If you have 2 piece jaws.  You can can machine the all to fit the top jaws., then turn it down to Id of the center.  Then expand the jaws out to grab it.


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## Ebel440 (Apr 11, 2015)

Just make an expanding arbor put a piece of round metal in the lathe a little larger then the Id. Drill and tap and countersink the end for a socket head screw.  Make a grove at the base of it to allow the mandrel to expand.  Then take it out and cut a few slits lengthwise.  Put it back in cut the od to match the part. Put a screw in and your done. Put the part on and put in screw and tighten.


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## tomw (Apr 11, 2015)

I just did something similar with a flywheel I am working on. I made a two piece mandrel, as diagrammed below. The hole in the mandrel base is tapped, the hole in the retaining plate is a clearance hole. Hopefully the diagram is relatively clear.


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## Nammar (Apr 11, 2015)

Have you thought of bolting your wheel to a faceplate? (If you have one.) A faceplate normally has at least four slotted holes and you secure the wheel to the faceplate using bolts and flat bar or large washers. You will need to use a DTI to adjust the wheel to centre. That's how I would do it. Geoffrey.


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## RVJimD (Apr 11, 2015)

The expanding arbor sounds like a useful item!  Off to the shop!


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## Cactus Farmer (Apr 11, 2015)

I needed to hold an item by the inside and build an expanding arbor by turning the OD, drilling and tapping a hole for a pipe plug and slitting the turned part. Pipe threads are 3/4" to the foot taper so it made to thing grow just enough to hold my part and I had all the things I needed to make it right there in the shop. Yes, it might wear out quickly but it was a two or three use tool. And all it cost me a little time. I've used the idea a couple more times since and it's a winner every time. Simple and fast for almost free, now your talking.........I keep bull plugs in all the common pipe sizes in a special place in the tool chest so I don't even have to go across the shop to find one, now is that being lazy or resourceful?


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## David S (Apr 11, 2015)

How about a piece like tomw shows with a pin to drive the spokes and the wheel can be held tight to the chuck with the tailstock.

David


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## JR49 (Apr 11, 2015)

Ebel440 said:


> Just make an expanding arbor put a piece of round metal in the lathe a little larger then the Id. Drill and tap and countersink the end for a socket head screw.  Make a grove at the base of it to allow the mandrel to expand.  Then take it out and cut a few slits lengthwise.  Put it back in cut the od to match the part. Put a screw in and your done. Put the part on and put in screw and tighten.


     Ebel440, or any "pros" Please help me picture this method.  "Make a grove at the base of it to allow the mandrel to expand".   Where is "the base of it" ?   "Put a screw in and your done",  I assume the screw is the same size and pitch that you tapped the end for, so what makes the round bar/mandrel expand without the tapped hole or screw being tapered ?  And, if it does expand, won't the screw threads just strip out when it expands ?  Please note, This novice is not questioning your knowledge, Just wanting to understand how to make an expanding mandrel before I get proficient at cutting tapered threads.  Thanks, JR49


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## aametalmaster (Apr 11, 2015)

I have a box full of arbors with threads on one end. Spacers take up the slop if the part isn't wide enough for the arbor...Bob


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## T Bredehoft (Apr 11, 2015)

_ "Make a grove at the base of it to allow the mandrel to expand"._

I would have said, make a series of slits, parallel the axis, dividing the arbor into quadrants.

_"Put a screw in and your done"_

Assuming a flat head screw, the conic section of the flat head would expand the mandrel. 

It's to be understood that the mounting surface (diameter) would have been to size and only needed expanded a couple of thousandths to be tight, so it wouldn't strip the threads.


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## Tony Wells (Apr 11, 2015)

Usually the threads tapped for such a screw are done with a taper tap, and kept fairly shallow. Then no matter what kind of screw you put in, when it hits the tapered part of the tapped hole, it forces the OD apart because of the splits. 

I have used this "spud" method in production many, many times and it works great.

My concern in this case would be the tendency for the ring to "sing" or chatter. I would opt to hold it closer to the OD if possible. The spud idea is worth a try though.


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## RVJimD (Apr 11, 2015)

Great ideas guys, thanks!

Here is my interpretation of the internal threaded expanding arbor.  I taped it full depth of the 5/16-18 tap and put a champher on the socket head to match the cone in the end of the arbor.


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## JimDawson (Apr 11, 2015)

Tony Wells said:


> Usually the threads tapped for such a screw are done with a taper tap, and kept fairly shallow.



I normally use a pipe tap for this, then use a pipe plug for the ''screw''.


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## Tony Wells (Apr 11, 2015)

Probably lasts longer, Jim. Mating tapers should be superior.


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## Bill C. (Apr 11, 2015)

RVJimD said:


> Great ideas guys, thanks!
> 
> Here is my interpretation of the internal threaded expanding arbor.  I taped it full depth of the 5/16-18 tap and put a champher on the socket head to match the cone in the end of the arbor.
> 
> ...



Could use a socket headed flat screw as well.  Still I like your tool.


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## Ebel440 (Apr 12, 2015)

I guess I could have been clearer in my explanation. But it looks pretty good. I use a screw that goes in a countersink. 82 or 90 degrees and countersink it almost as deep as the head. I also cut In at the base so there's a radial groove to maybe? Allow it to expand easier.


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## Bill C. (Apr 12, 2015)

Now I am curious how many of these are you planning on making?


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## RVJimD (Apr 12, 2015)

Bill,

I guess you mean how many wheels and not how many arbors?  I plan to make 12 spoked wheels.  I guess you are thinking, as am I, holy cow that is going to be a lot of tedious RT work!

If I was finished with one wheel after the initial milling that would be one thing.  But, then I need to switch to a chamfer cutter and follow the five spokes.  "Ya, I love how they look but oh boy this is a bunch of work!"  And, "man I wish it was inexpensive, quick and easy to convert my mill to CNC".

Jim


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## Bill C. (Apr 12, 2015)

Jim,

Thanks for the reply. I was thinking you were planning on selling them online and building up your inventory.  Maybe you can find a buddy with a CNC mill to cut all those cavities.  

They do look good.


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## RVJimD (Apr 12, 2015)

Bill,

I wanted to do a spoked wheel just to learn how to do it for myself, and my brother-in-law wanted me to make him the new wheels but I was the one that said, "oh sure, no problem, let's make them 5 spoked so they look good"  I will probably do them myself, even though I do actually have a friend very near that has converted his mill and could do them quite easily.  I may end up doing one or two set of three with simple bolt circle lightening holes.  My biggest issue to solve now is putting a nice finished chamfer on the edges of the spoke and radii of the inner and outers.  I am learning how much work all the "little" detail adds!

Jim


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## Bill C. (Apr 13, 2015)

They do look nice and strong.  Pride is in the details. Some of us will be touching a part up until they take it away from us.  I was told polishers that finish plastic molds never get finished because there is always one section that needed touching up till they haul the mold out of the shop.  

Have a nice week


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## Billh50 (Apr 13, 2015)

when I did mold making for plastic bottle molds we had to polish them till they had a mirror finish with no visible hair line scratches. If you saw a scratch when polishing you had to go back to sand paper and using several grits work your way back to polishing. It sometimes became a long process.


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## Bill C. (Apr 13, 2015)

I had heard that too. Plastic shows everything.  One of my instructors told the class women were good at it because they had more patience and stronger fingers.  As you know that class of tool steel is extra tough to begin with.  I don't think I could do it.  I was doing good to hand finish aluminum form blocks when I was working in St.Louis. They would assign me a rough cut block of aluminum and a steel template with instructions. At least they paid well for doing it.  The blocks were used in hydro-form press to wrap a sheet of aircraft grade aluminum to shape the blocks. About a year and half later the whole project was scraped.


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## Billh50 (Apr 13, 2015)

It took 2 - 3 weeks to complete  2 double cavity molds. We would start with a die grinder to get the rough spots and blend the parting lines. Then go to sandpaper by hand. Then a buffing pad on a die grinder til it shined.


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## Bill C. (Apr 14, 2015)

WOW, that type of steel is tougher than most tool steels due to the shock load properties.  I would have assumed it would take longer to polish out the tool marks. You weren't wasting time on that project.  Probably a dirty one as well.  

Thank for your reply.  I hope you have a great day.


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## Billh50 (Apr 14, 2015)

You learn a lot of short cuts along the way. I use to tell many of the apprentices " I may not know the trade that well but I sure know a lot of the tricks of the trade." Some of those tricks made me look real good at a few jobs along the way.


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