Thread: MT5 adapter wearing out.

attached a pic which shows wear and tear forming on the rear of the MT5 adapter, as well as the spindle taper.
whats odd is that when either using the adapter or MT5 test bar, it loosens up quickly when running the lathe, even if lightly banging it in, which takes some effort to get out when the lathe has not been run.
at first it looks like rust, best guess is that when the cast iron MT5 adapter wears it forms a type of copper color dust.
seems to be traveling further up the adapter the longer it's used and can't decide if either using lapping compound, or wrapping 1200 sand paper around the adapter and spinning it in the spindle would sort it out.

Is it possible that the taper bearings are transferring an out of round bore or (misaligned bores) back through to the spindle taper causing an egging of the spindle ? as neither quick fix would solve the problem

Hi

Did you clean it very well?
Have you blued the taper to see if its seating correctly?

Stuart

What's the machine? Are you sure the spindle taper is MT5? Because that adaptor appears to have no wear except on the end. Blue will reveal all.

spindle and adapter were cleaned, did not have this problem on my previous lathe.
the lathe is new and similar to an al 540, using the adapter supplied with the machine.
The problem gets worse when applying more preload to the taper bearings, and turning the spindle by hand causes the adapter to eject.

Had blued both the adapter and MT5 test bar.
looked like a small section of the rear when blued is not making contact, trying to determine if it's due to the taper not being ground correctly, or caused by uneven bores.
what's strange and makes me assume it's the uneven bore being transferred from the taper bearings is that when lightly giving it a tap in the spindle it takes a good hit, using 35mm wood rod to get it out the spindle when the lathe has not been run.
repeating this and only running the lathe on 45 rpm, it quickly loosens up.

Lather have you fitted your test bar and checked it with an indicator ? what did that tell you ?

maybe even test while you adjust the preload ?

This would be the first time I have heard of a spindle bending under preload, unless the spindle was damaged/bent sometime previously and the preload is trying to pull it straight ?

the readings using a test bar were not consistent.
runout is around 0.01mm, though there are inconsistent jumps of +/ - 0.01.
test bar has to be constantly reinserted as it kept coming loose.

Originally Posted by lather

spindle and adapter were cleaned

Figured it would have been but I had to ask.

Originally Posted by lather

looked like a small section of the rear when blued is not making contact, trying to determine if it's due to the taper not being ground correctly, or caused by uneven bores.

Are you sure you are reading the blue correctly?
If the rear isnt making contact how can it be getting wear and tear?
Though we are rapidly heading out of my depth and I've run out of simple ideas.

Stuart

Hi Lather,

Just a dumb idea, is it possible that it's a little bit oval shaped, so that it appears to seat and blue ok, but when it rotates a little it come loose.

Other than that... no idea?

Regards
Ray

Stuart, most of the rear surface is making contact, though there was a small patch that seemed to have more blue due to there being less contact, though overall it looked as if 90% of the surface had contact.

Ray,
the spindle itself could be oval, and difficult to measure due to inconsistent jumps,
the reason i asked if it was possible for an egged bore to transfer it through to the spindle taper is that it's happening on the rear of the adapter, were the taper bearing sits on a thinner part of the spindle, the front part of the taper is on the more solid spindle flange.

HI,
I certainly wouldn't be using Sandpaper in the Spindle. It certainly sounds like that You have some sort of Problem with the Spindle. The Lathe should have a Warranty so let the Supplier sort it out. Personally I have a Hafco AL-960b Lathe, I have used the Supplied MT5 Adapter with a MT3 Test Bar and I have used a MT5 Test Bar straight into the Spindle with No Problems either way - My Spindle Runout is Consistant.

something has to be flexing the shaft if the tapers pop out when you turn the spindle, maybe one of the gears has not been machined properly and is not concentric to its shaft ????

can you check that one of the gears is not meshing against a gear on the spindle too tightly at some point of rotation,

I know it sounds far fetched and if that was the problem you should feel a tight spot, maybe even 0.01 mm ?

Stuart,
forget the sandpaper, i think the best thing to use in the spindle is a stick of dynamite

shedhappens,
The adapter was ejecting when in neutral, with no gears meshing when turned by hand.
the gear clearances seem o.k. , though the splined gears have a fair amount of play on the shafts.

Maybe you should be trying to correct these inconsistent bumps in the spindle bore 1st ,it dosent sound good.

Originally Posted by lather

... the lathe is new and similar to an al 540,.. .

Sorry if this has already been covered, but is it still under warranty?