# Expanding mandrel a la John Stevenson



## DickDastardly40 (Apr 4, 2009)

This is a blatant copy of a post JS put up either here or one of the other sites:











The cross cuts were done with a hacksaw, the taper on the capscrew is 6 deg (which my compound is generaly set to anyway)






It doesn't require too much tightening to grip enough to bring my eccentric straps to thickness






If it looks like there's a lot of overhang it's because I wasn't sure how much I'd need to extend the cuts to get expansion and I didn't want to cut too much off the piece of steel.

Thanks John.

Al


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## John S (Apr 4, 2009)

Please send royalty payment ASAP. 8)

JS.


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## DickDastardly40 (Apr 4, 2009)

Buy you a pint or two at Harrogate?


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## Metal Butcher (Apr 4, 2009)

Sorry to but in. But Since I am an Ohioan... and from the U.S.A... My natural curiosity needed satisfaction.

This will help to stop others like me from scratching their head. 

Quote: Harrogate is an alcoholic beverage or cocktail made with vodka, archers (peach schnapps), malibu?, fresh orange juice, fresh pineapple juice, and fresh cranberry juice.

Sounds more like a "health drink"!With the vodka giving it purpose! ;D

On topic...I have looked at buying an inexpensive steel expanding mandrel set. Since they look really simple I may try to make one from aluminum for a one time future use.

Is there any reason that aluminum shouldn't used?

Edit:I just had an idea! I was given a good amount of tapered reamers along with a box of tapered pins. The Father of the fellow that gave them to me worked as a machinery repairman. The reamers start at a small .070 and go up to #10. Could this be a quicker and easier way to make and use an expanding mandrel. 

Any thoughts?

Cheers! -MB


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## Tin Falcon (Apr 4, 2009)

MB:



> Buy you a pint or two at Harrogate?


This is referring to the National Model engineering Expo in Yorkshire England 8-10 May 2009. 
I would expect DD is offering to buy a pint or two of Ale or Cider for Jonh not some fancy fruit juice drink. LOL that was a good one though. LOL
Tin


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## Metal Butcher (Apr 4, 2009)

Tin Falcon  said:
			
		

> MB:
> This is referring to the National Model engineering Expo in Yorkshire England 8-10 May 2009.
> I would expect DD is offering to buy a pint or two of Ale or Cider for Jonh not some fancy fruit juice drink. LOL that was a good one though. LOL
> Tin



DARN!, Its my bad eye sight again! I miss-read the word "at" as the word "of".

I had my small old monitor zoomed out to see a full views of the pictures.

I really think the blame should go to member mklotz for teaching the Ctrl plus scroll wheel trick to zoom in and out. LOL :big:

Try to read after zooming waaay out. You see, NOT MY FAULT! LOL.

I'm glad you enjoyed my previous post. ;D

-MB


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## mklotz (Apr 4, 2009)

Metal Butcher  said:
			
		

> I really think the blame should go to member mklotz for teaching the Ctrl plus scroll wheel trick to zoom in and out. LOL :big:



Note to self: stop teaching old dogs new tricks.


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## Debian (Apr 4, 2009)

About the Model Engeenering show in Harrogate, Yorkshire, in may.
I would like to take a plane for a visit, but I would like to know, from who knows something about that, if there are also i.c. model engines or only steam, train and meccano things.
Didn't find good informations on google.
Thanks very much

Paolo


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## Stan (Apr 4, 2009)

> the taper on the capscrew is 6 deg (which my compound is generaly set to anyway)



How to you cut tapered threads with the compound?


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## Metal Butcher (Apr 4, 2009)

Stan  said:
			
		

> How to you cut tapered threads with the compound?


 
If your question refers to this thread on expanding mandrels, then the taper is just on the sides of the screw head and on the outer end of the mandrel bore.

 The threads below the tapered screw head and below the tapered bore are standard with no taper.

-MB


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## John S (Apr 4, 2009)

Debian  said:
			
		

> About the Model Engineering show in Harrogate, Yorkshire, in may.
> I would like to take a plane for a visit, but I would like to know, from who knows something about that, if there are also i.c. model engines or only steam, train and meccano things.
> Didn't find good informations on google.
> Thanks very much
> ...



There are IC engines amongst the club stands and some nice ones.
Let me explain how our shows work as they are very different to the ones in the US.

First off these are very commercial as opposed to a group of people getting together and as such they have to pay. 
Payment comes in two forms, the punter at the door and the trade stands, some of the trade stands can be in the high thousands so they need to present their wares.
The result is everything is on show from a packet of split pins up to a Bridgeport, I don't think there is anything main stream you can't see or buy.

Because the punter needs to be kept happy and just buying tools doesn't rev everyone up they have the models and this is where the shows vary.

In the UK you can't display a model on your own, you need to belong to a club because the various clubs get given, free, a stand to display their members work and man it thru the show to answer questions.
Now how many IC engine builders there are to steam, trains etc is down to club membership.

This is a few from previous years.

http://modelenginenews.org/shows/harrowgate2006/index.html

http://www.rcgroups.com/forums/showthread.php?p=3717130

Harrogate is the biggest show in the UK gate figures over three days can easily top 20,000.

The Bristol show in August is unique in that the Bristol club have an IC section that's very well represented and they put two stands on, one for IC engines and one for turbines, no other show does this as far as I know.
The Bristol show is far smaller and a lot more relaxed as that one isn't so commercial being run by the club itself.

.
JS.


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## Stan (Apr 4, 2009)

Thanks MB. Makes sense. I have made mandrels using pipe plugs into a pipe thread and had that stuck in my cranium.


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