Pen mandrel shaft diameter

[michaelperez]

Hello,I hope you are doing well. I would appreciate your feedback.

I just started pen turning about a year and I have the Axminster pen mandrel compressor. When I looked for a replacement shaft, I noticed there are two diameters available: 0.242" and 0.246". Is the 0.246" diameter intended for specific bushings to achieve a better fit?

Thank you!

 

[egnald]

Here is what I know about mandrels.

Berea (BereaHardWoods Co. Inc.), who was involved in the very early days of developing pen kits, specified the "standard" pen turning mandrel shaft which they later referred to as an "A" mandrel. According to the Berea specification, the "A" mandrel is 0.247" inches +0 / -0.002" inches in diameter. Most bushings are designed to accommodate this size of mandrel.

However, to make supplying mandrels easier, most manufacturers fall back to one of two standard Drill Rod sizes rather than making a custom mandrel that meets the 0.247" inches +0 / -0.002" inches specification. They consist of the "D" sized Drill Rod and the "C" sized Drill Rod. According to your post, I would assume that Axminster has done the same. Size "D" Drill Rod is specified as 0.246" inches +/- 0.0005" inches typical and is a very good replacement for most standard 0.247" inch "A" mandrel shafts. The alternative is "C" Drill Rod which has a slightly smaller diameter of 0.242" inches +/-0.0005" inches.

Although all bushings should fit on the smaller, "C" (0.242") mandrel, I personally, I use the larger "D" Drill Rod (0.246"). For most of the bushings I have, it does provide a better fit; however, when I come across a set of bushings that feel to tight on it, I swap it out for a "C" size. So, I actually use both sizes depending on how tight a particular set of bushings feel.

Regards,
Dave

PS If your Axminster system does not have a threaded mandrel, you could do what I do. I buy 3 foot lengths of "C" and "D" Drill Rod and cut them down to about 12" inches to make my mandrels. Of course, if the Axminster mandrels are threaded, you will likely need to buy a replacement that is also threaded.

 

[michaelperez]

Here is what I know about mandrels.

Berea (BereaHardWoods Co. Inc.), who was involved in the very early days of developing pen kits, specified the "standard" pen turning mandrel shaft which they later referred to as an "A" mandrel. According to the Berea specification, the "A" mandrel is 0.247" inches +0 / -0.002" inches in diameter. Most bushings are designed to accommodate this size of mandrel.

However, to make supplying mandrels easier, most manufacturers fall back to one of two standard Drill Rod sizes rather than making a custom mandrel that meets the 0.247" inches +0 / -0.002" inches specification. They consist of the "D" sized Drill Rod and the "C" sized Drill Rod. According to your post, I would assume that Axminster has done the same. Size "D" Drill Rod is specified as 0.246" inches +/- 0.0005" inches typical and is a very good replacement for most standard 0.247" inch "A" mandrel shafts. The alternative is "C" Drill Rod which has a slightly smaller diameter of 0.242" inches +/-0.0005" inches.

Although all bushings should fit on the smaller, "C" (0.242") mandrel, I personally, I use the larger "D" Drill Rod (0.246"). For most of the bushings I have, it does provide a better fit; however, when I come across a set of bushings that feel to tight on it, I swap it out for a "C" size. So, I actually use both sizes depending on how tight a particular set of bushings feel.

Regards,
Dave

PS If your Axminster system does not have a threaded mandrel, you could do what I do. I buy 3 foot lengths of "C" and "D" Drill Rod and cut them down to about 12" inches to make my mandrels. Of course, if the Axminster mandrels are threaded, you will likely need to buy a replacement that is also threaded.

Hello Dave, thanks so much for all the detailed and valuable information, feel so grateful.
It's been difficult for me to find replacement shaft but yesterday I found that woodturningz carries the holdfast shaft in the 2 sizes D and C.
Please where do you buy the drill rod ? Is it the same or the one that holdfast sells are special.
Holdfast are 7.5 each plus 9.5 shipping

 

[egnald]

Hello Dave, thanks so much for all the detailed and valuable information, feel so grateful.
It's been difficult for me to find replacement shaft but yesterday I found that woodturningz carries the holdfast shaft in the 2 sizes D and C.
Please where do you buy the drill rod ? Is it the same or the one that holdfast sells are special.
Holdfast are 7.5 each plus 9.5 shipping

I get Drill Rod from McMaster Carr in the USA. I think that any industrial supply type of business would have it or would be able to get it. It is something that a machine shop would buy. That's how I learned about it, I used to work for a company that did equipment design and fabrication. - Dave

 

[michaelperez]

Thanks so much sorry to bother again but which would you recommend
Hardened undersized high speed mt2
Hardened oversized high speed mt2
Tight tolerance multipurpose oil hardening -O1 tool steel rod
Tight tolerance easy to machine W1 tool steel rod
Also I saw stainless steel types
I'm confused which one to choose
Greetings and thanks again

 

[egnald]

I used the standard oil hard one (not oversized or undersized). No need for stainless steel. A 3 foot length cost about $9 USD — it wound up costing about $3 USD per mandrel. - Dave

 

[michaelperez]

I used the standard oil hard one (not oversized or undersized). No need for stainless steel. A 3 foot length cost about $9 USD — it wound up costing about $3 USD per mandrel. - Dave

Thank you so much, I really appreciate your time and all the information.
Sincerely wish you a nice weekend.

 

[rherrell]

I keep letter "D" W-1 rod in stock if you need some.

 

[Woodchipper]

Dave, thanks for your reply. Never thought of a DIY mandrel. We have some sources here in town that might work for the drill rod.