I find myself turning a lot of relatively thin and flat disks (like washers and such) lately. I have been wondering if anyone knows of a (semi-)universal mandrel that will hold a variety of parts with different centers and thicknesses. Any thoughts? I hoping for something I can make for myself.
-
Welcome back Guest! Did you know you can mentor other members here at H-M? If not, please check out our Relaunch of Hobby Machinist Mentoring Program!
Universal Mandrel??
- Thread starter walterwoj
- Start date
- Joined
- Oct 14, 2013
- Messages
- 997
Superglue arbor, or maybe a magnetic chuck?
Sent from my SM-G715A using Tapatalk
Sent from my SM-G715A using Tapatalk
- Joined
- Dec 3, 2017
- Messages
- 1,911
Harold Hall wrote a book in which he described making collets for this application. He called them thin piece collets I think. Basically, you make a collet with several different shallow depth diameters. It’s a good idea, but I never made one.
homews.co.uk
Harold Hall's Workshop Practice Series Books
"Model Engineers' Workshop Projects" Workshop Practice Series book 39,
- Joined
- Sep 10, 2022
- Messages
- 930
Small sizes under an inch, you can use the collets as mentioned. They work fantastic. Or you can also go this route and make spacers for your 3 jaw chuck. Grabbed this photo off the web.
Cutting oil is my blood.
Cutting oil is my blood.
- Joined
- Jul 28, 2017
- Messages
- 2,387
"Universal" is quite a high bar. I tend to make one-off holders for one-off projects, the requirements are so variable that it seems hardly worthwhile to design and build something that may turn out to not be suitable for the next thing I'm working on. For example, sometimes the critical dimension is the OD, others it's the ID, sometimes it's the thickness. Different requirements can dictate different approaches to the machining problem.
I use purpose-made expandable mandrels all the time since they're not all that difficult to make. I have an expandable mandrel set but in reality they rarely suit the job at hand.
I use purpose-made expandable mandrels all the time since they're not all that difficult to make. I have an expandable mandrel set but in reality they rarely suit the job at hand.
Yes, gripping thin material in some universal manor to make a washer is a mystery to me. So I would like to better understand how others do it. I have made thin material cuts but usually one can find a place to put a screw at an edge to hold it. It is more difficult when one does not have room or the material is not thick or stiff enough to be held this way.
I needed to make two smooth 0.020" thick flat ring washer from something smooth, hard and non-magnetic. They went into a ball bearing race way with ceramic balls. I needed two of them, on on each side of the balls. They were to fit into a given raceway so the final OD of about 2.5" and an ID of about >2.25" was called for (Accurate size, but I just do not recall the dimensions now). So the washer width was less than 0.25" wide. Steel is out as well as stainless due to the magnetism. (Even non-magnetic stainless turns magnetic when worked. and I wanted no magnetism.) Al, Cu, or Brass would have been too soft for the application. There are other possible NON-magnetic materials, but finding a thin sheet was a bit of a challenge. So I found some thin, but reasonably priced Ti sheet and purchased it knowing full well that it was going to be difficult. I took a 3" dia piece of Al rod about 4 inches long and surfaced the end smooth. This was the holding surface. Then I used some high temperature hot melt glue to stick the Ti sheet on with. I used a hot plate. I went slow and actually used a point cutter I made of HSS. I had to resharpen it several times as it was more of a scrapping tool than a cutter. I cut the OD and then came back and cut the ID. The large piece of Al was pretty good about carrying the heat away, so that the glue would not melt. After I made one washer I got over confident and tried to speed the process up ... and the part came loose when cutting the ID. The rubbing melted the glue! I used hot melt glue so that I could get it back off and clean it when finished. I had to try again using the slower speeds. There is probably a better way to do this, but .... it worked. Other than a little bit of oil I had no way of cooling the tool and material as I went. If I had had diamond tooling or even carbide at the time I might have tried it.
I needed to make two smooth 0.020" thick flat ring washer from something smooth, hard and non-magnetic. They went into a ball bearing race way with ceramic balls. I needed two of them, on on each side of the balls. They were to fit into a given raceway so the final OD of about 2.5" and an ID of about >2.25" was called for (Accurate size, but I just do not recall the dimensions now). So the washer width was less than 0.25" wide. Steel is out as well as stainless due to the magnetism. (Even non-magnetic stainless turns magnetic when worked. and I wanted no magnetism.) Al, Cu, or Brass would have been too soft for the application. There are other possible NON-magnetic materials, but finding a thin sheet was a bit of a challenge. So I found some thin, but reasonably priced Ti sheet and purchased it knowing full well that it was going to be difficult. I took a 3" dia piece of Al rod about 4 inches long and surfaced the end smooth. This was the holding surface. Then I used some high temperature hot melt glue to stick the Ti sheet on with. I used a hot plate. I went slow and actually used a point cutter I made of HSS. I had to resharpen it several times as it was more of a scrapping tool than a cutter. I cut the OD and then came back and cut the ID. The large piece of Al was pretty good about carrying the heat away, so that the glue would not melt. After I made one washer I got over confident and tried to speed the process up ... and the part came loose when cutting the ID. The rubbing melted the glue! I used hot melt glue so that I could get it back off and clean it when finished. I had to try again using the slower speeds. There is probably a better way to do this, but .... it worked. Other than a little bit of oil I had no way of cooling the tool and material as I went. If I had had diamond tooling or even carbide at the time I might have tried it.
- Joined
- May 7, 2023
- Messages
- 1,399