7 mm mandrels

[richard grantham]

Does anyone make true 7mm mandrels ?? just bought one ( supposedly) and found out its 1/4". was told by salesman all mandrels are really 1/4" to take 7mm sleeves. I want to drill 7mm hole, put on 7mm mandrel, and turn, then use predator calling reed holders without extra step.
Help-- I use #2 morse taper.
Richard

[Grant Wilkinson]

I believe that you will find that this one 88K69.02 in Lee Valley is a true 7mm. You could write to them to confirm.

Grant

[Paul Heely]

McMaster Carr, and probably other supply houses, sell lengths of drill rod. McMaster shows 7mm as being a size they sell. You could have a machine shop thread the end and put a taper in the end for the tail stock. I would think you would need to hold the other end in a collet or chuck since I'm not sure how easy it would be to attach a morse taper to the other end.

Second idea.....
Use a standard "A" mandrel with a set of bushings, bought or turned, that measure 7mm on the outside.

Good luck.

--
Paul

[Randy Meijer]

I believe that you will find that this one 88K69.02 in Lee Valley is a true 7mm. You could write to them to confirm.

Grant


Entirely compatible with kits that require a standard-diameter "A" mandrel, this is a convenient and fast method of securing blanks for turning.

It appears that the Lee Valley mandrel referred to, is just a standard "7mm" mandrel that is just under a 1/4" in diameter.

Not sure I understand why you need to do this; but the simplest solution would be to use a "7mm pen" tube on your 1/4"(actually around 0.246")pen mandrel as a sleeve and don't glue it into your blanks. Buying a piece of 7mm drill rod will also work; but you will have to drill a centering dimple in the end of the rod for the live center or you will need a rotating Jacobs chuck for your tailstock. There are several other ways to accomplish what you want to do but are a little more complicated(requires additional tools).

[Marvin Hasenak]

I use a 1/4" steel rod in a collet chuck that I threaded one end and drilled a centering pilot on that end for the live center. That and cone shaped bushings that center the call has worked for me for years, along time before pen mandrels were even heard of. You can use the pen mandrel the same way.

I drill the blank with a 9/32" bit so it will hold the JC Product reed sleeve. The cone shaped bushings are just small pieces of wood that I drilled a 1/4" hole in and then turned on the mandrel. Also have some Delrin bushings but those are made out of scraps and are no better than the wood bushings.

[richard grantham]

Thanks for suggestions. I have done the 1/4" standard mandrels with 7mm pen spacer tubes- worked pretty good, some slipplage and tubes were hard to get out of some wood. Marvins suggestion was what I had settled on before quitting turning ( got the bad old C stuff in liver and chemo is killing me ), only problem with tapered plugs I turn tapered bells in one end of calls and mangaged to split some pretty wood when I tightend nut on mandrels. I have a new maxi mandrel which is adjustable for length and has #2 adjustable collet for the 1/4" shaft, plus if I do buy or make a true 7mm I have center drills for end and can use drill chuck in headstock for a collet.
Thanks to all, ps just got a PM refering me to a guy that makes mandrels to order !!!!
Richard Grantham

[Randy Meijer]

.....Thanks to all, ps just got a PM refering me to a guy that makes mandrels to order !!!!
Richard Grantham

Yeah. I forgot about that option. Would you be talking about jcollazo out of California?? I purchased a mandrel from him and it was just fine. Only problem is that he is making standard size mandrels and probably would not have 7mm rod in stock. It might be more economical to make your own, especially if you already have a die so you can thread the TS end. Certainly wouldn't hurt to email the guy, however.

[Marvin Hasenak]

Here is another option if you get a 7mm rod. http://penmakersguild.com/articles/pinchuck.pdf

They refer to it as a pin chuck, I always called it a pin lock mandrel, but I got the idea from a machine shop. I have some that I made that are 5/8", 1/2", 3/8", and 1/4" in diameter. For the pins I use small nails that I cut the head of and cut to length. The 1/4" does not work as good as the larger ones because of the actual locking method and the small surface where it engages. On the 5/8" bore on open reed calls these work like magic. These mandrels stuck in a collet chuck and you are in business with no cone bushings.

Another thing on the cone bushings, as soon as I have the blank turned round I let off on the nut to reduce the pressure on the bell end of the call. This saves a lot of splits in the bell end.

Right now that is about all of the tricks that I can think of