Bent spindle on my DELTA DP220

[Douglas1968]

Hey guys, I love this machine and could use a little advise on fixing this spindle problem.

[SteveM]

It would be hard to give a precise answer without seeing the machine.

Whacking it might get it to run true, but might mess it up more and can definitely harm the bearings.

You might have to pull the spindle to measure it. What you do will depend heavily on where it is bent.

You could lay it on a surface plate or other flat surface on a pair of V blocks and just see what a dial indicator shows at different points. The surface doesn't have to be precision, as you are not measuring in different spots, just spinning it and seeing how much that spit moves. A table saw table would work fine.

You should look at Keith Fenner's youtube channel:
https://www.youtube.com/user/KEF791/videos
He does a lot of shaft straightening, as his business is heavy in marine repair.

His straightens shafts with a press and with a torch. He also has a neat tool that cradles a shaft on bearings and swivels to ensure that the shaft can move freely.

Steve

[Atkinson_Railroad]

In addition to the tip already suggested,

Scroll to page 316 (13-3) of the PDF here: http://www.woodworkslibrary.com/reposit ... airman.pdf

It’s a Navy Publication that can provide additional ideas.
Unfortunately the document doesn’t cover “spot heating” which can also straighten shafts.

Stranger things have happened. I was shocked to learn a spindle was still available for
a 1960’s era Craftsman drill press. You should investigate if a spindle for the Delta machine
is still available somewhere. (It’d be a long shot, but ‘Ya never know.)

John

[Douglas1968]

Thanks guys, I’m looking right now for a set of V Blocks. I’ll take it from there.

[Douglas1968]

I believe I’ve narrowed it down. I’m not sure if theirs hope for her, but then again I’m learning along the way.

[Douglas1968]

Oops

[spro]

For a test as this, it should be done between centers.

[spro]

Holding one end in the most perfect chuck isn't the way because it needs support at the end. That means both ends of their original center are clean and can reliably seat upon centers. It doesn't matter if your lathe is perfect center at this time. What does matter is the relative difference between one side to another of your DP spindle. Re center the indicator and note where it shows max deflection of the spindle between the upper and lower bearings. That area may need bent back before addressing the nose.

[Harold_V]

In order to determine the state of the taper, where the chuck mounts, the shaft should be mounted such that the two bearing surfaces are concentric with one another. Hold the one end in a four jaw, as was displayed, with a steady rest running on the opposite bearing seat. If run-out is due to the shaft being bent between the bearing surfaces, that area will not run true when installed as suggested. Assuming it runs true, the indicator should then be placed on the taper. If it's bent (most likely), you'll be able to read the amount. Holding the shaft, as shown, leaves too much room for error in determining where the shaft is not true.

Same test can be accomplished with V blocks, but in both cases, the critical place to locate is on the bearing seats. What you're trying to determine is if the end is concentric with those two surfaces.

H

[earlgo]

When you get so you know where the bend is, then you are going to want to straighten the bend.
If you have a mill table this would be one way to gently persuade the bend in the right direction. (The photo shows how a screw was straightened, but the principle is the same.) Mount the v-blocks at the bearing mounting points, and using a clamp, apply gentle pressure until it springs back to where you want it.

I know that this is mill table abuse, but it beats hammering on the part.
I prefer this to mounting the item in the lathe between centers and pushing with the tool post screws, although it can be done like that if there is no other means.
Maybe this will cause a better method to be thought of.
--earlgo

[Harold_V]

For long slender items, that's a great setup, --earlgo. It offers one complete control, so over correcting should be limited, if not eliminated.

The only thing I'd worry about is in trying to straighten large cross sections, or very short pieces, where the extreme pressure required to bend the item might risk pulling out a T slot. Beyond that, I see no abuse to the table.

I like to place shims (I use aluminum) between surfaces, to prevent displacement (denting) of metal. That would be very important on threads.

H

[SteveM]

The only thing I'd worry about is in trying to straighten large cross sections, or very short pieces, where the extreme pressure required to bend the item might risk pulling out a T slot. Beyond that, I see no abuse to the table.

You could clamp the part to the table on the ends (using several clamps, if needed, to distribute the load) and use a jack to push UP to bend it.

Steve