Recently I've been noticing an odd warping in both wood and acrylic blanks. I will turn one side of the blank down, then go work on the other side, and when I go back to the first side, it's warped and makes my tools bump. I have a suspicion it may be my mandrel. It's had 3+ years of pretty constant use. Do I need to replace my mandrel, or is there a different issue? Thank you!
Signed-In Members Don't See This Ad
Signed-In Members Don't See This Ad
jttheclockman
Member
Rod is probably bent from overtightening or poor care. Many times we throw them on the bench and things fall on them or something like that. You can buy replacement rods. Take the rod and roll it on a true flat surface like the tablesaw top and see if it wobbles.
Kenny Durrant
Member
I agree with John. I don't think they wear out just other issues he mentioned. I bought a mandrel saver and love the thing. It took some getting used to as far as how tight or how much pressure to put on the blanks but that was also a problem with being too aggressive when first starting to turn the blank. When I take it off the lathe I put it in a plastic case that it came in or if left on the lathe I slide the tail stick all the way up to protect it from something falling on it or someone hitting it. I work out of my garage so I'm not the only one in and out.
I would recommend that you learn the technique of "Turning Between Centers" or TBC. . Look in the IAP Resources for articles.
You can then avoid the use of bushings and mandrel and achieve very accurate results. . You will need a vernier caliper, preferably with digital readout, but you probably have that already.
You can then avoid the use of bushings and mandrel and achieve very accurate results. . You will need a vernier caliper, preferably with digital readout, but you probably have that already.
RobS
Member
Also, not having the lathe on a flat surface will lead to this effect. I recently upgrade my table top to a true flat surface and the issue was resolved.
egnald
Member
Greetings from Nebraska.
As others have already mentioned, TBC and Mandrel Savers can be a nice enhancement. Although I have started doing more TBC work, I usually use a mandrel - the adjustable/replaceable kind with a Mandrel Saver tailstock.
The actual mandrel shaft I use is a length of "D" Drill Rod that I buy from Granger. It is 3-feet long and 0.246 inches in diameter. (Sometimes my 7mm slimline tubes feel a little tight on it so I also have a piece of "C" Drill Rod that is 0.242 inches in diameter). Since a 3-foot piece only costs about $6 bucks my cost is only $2 per mandrel shaft so I repurpose them whenever they start running a little out of true or if they get galled up from bushings, etc.
Regards,
Dave
As others have already mentioned, TBC and Mandrel Savers can be a nice enhancement. Although I have started doing more TBC work, I usually use a mandrel - the adjustable/replaceable kind with a Mandrel Saver tailstock.
The actual mandrel shaft I use is a length of "D" Drill Rod that I buy from Granger. It is 3-feet long and 0.246 inches in diameter. (Sometimes my 7mm slimline tubes feel a little tight on it so I also have a piece of "C" Drill Rod that is 0.242 inches in diameter). Since a 3-foot piece only costs about $6 bucks my cost is only $2 per mandrel shaft so I repurpose them whenever they start running a little out of true or if they get galled up from bushings, etc.
Regards,
Dave
leehljp
Member Liaison
And another problem is the "ends not square"- and then tightening the end nut. That can cause a minuscule bow/bend in the mandrel rod. Most of the time it will probably straighten after the tension is released.
Another reason for TBC.
Another reason for TBC.
As Hank just said, immediately above, having the blank ends square to the blank axis is very important .
I find it is hard to drill straight unless the blank ends are first squared.
For my way of doing things, that means .... (0) roughly, but closely, square the ends, (1) round the blank, (2) square the blank ends, (3) drill
And I do the drilling on the lathe.
I find it is hard to drill straight unless the blank ends are first squared.
For my way of doing things, that means .... (0) roughly, but closely, square the ends, (1) round the blank, (2) square the blank ends, (3) drill
And I do the drilling on the lathe.
Last edited:
rherrell
Member
Get yourself a dial indicator and learn how to check your mandrel for run out. Here's a video I made on checking a pin chuck for run out, it's the same process with a mandrel.
Pin Chuck Video
Pin Chuck Video