Rotary Table Failure

Paul is this a second rotary table and third gear you have stripped? I only ask as last year you showed this photo which is of another table going by the oil grooves and this post is about a Yuasa that has stripped two gears in the same way. Does seem a bit odd that 3 gears strip for one user?

My thoughts are that some of the work you are expecting this size table to do on your half scale traction engine may be beyond its design purpose rather than it being unfit for purpose.

Edited By JasonB on 18/08/2016 14:20:20

Jason.

Interesting photo, if you look towards right hand side where the tooth removal is worst and then move your eyes to the left, it looks like the worm wound out of engagement just leaving a scar.?

This is a replacement for the rotary table (which I purchased second hand) and purchased a replacement worm gear after it was damaged. BUT, because of previous experience, I used a smaller diameter cutter, made sure that the RT gears were fully engaged and only made light cuts to reduce the loading on the gears. Used conventional milling direction and had table clamps lightly engaged to eliminate backlash problems.

The worm gear is very soft and cuts easily with a file. Not sure but think it is cast iron. The broken teeth had crumbled and not sheared off, like it would with steel.

My main complaint is the way Yuasa have responded. I would have accepted any reasonable offer for a replacement part but now will push then further, even if only for my satisfaction.

Paul

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Spot on, Paul ... We're with you all the way.

MichaelG.

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P.S. ... Regarding the crumbling of the teeth:

It looks like a simple matter of weak design, and/or poor material ... But one possibility might be that you were getting high frequency chattering [starting at the cutting tool, but feeding back to the worm/gear interface]: It's therefore conceivable that your gentle feed might have been counter-productive, and that more pressure would have overcome any backlash. That said: the thing is still clearly not fit for moderate work, and, if it was only intended for indexing and drilling, then they should have said so !!

I suppose it depends on moderate work, cutting weld prep chamfers on 10mm steel boiler plate would be a cutting length of around 14mm and an insert cutter needs a bit more force than an HSS one.

the 10" dia cuts through the boiler plate may also just have been beyond what teh table is really capable of.

Wormwheel on mine looks to be cast iron don't know if they use SG or just plain old grey iron probably the later.

I would be interested to know what others feel is the sort of work a 6" table should be fit to perform? Having only done engineering as a hobby I have always treated my machines as such, do those in industry expect more from them?

Edited By JasonB on 19/08/2016 08:43:27

The last job with the replacement gear wheel was not as heavy as when I machined the boiler plates. Cleaning up the perimeter of a 7" dia plate (previously cut roughly to size with an angle grinder), 6mm thick, 8mm cutter, less than 1mm deep and 1-3mm wide cuts. Slow feed with the RT clamps slightly on.

Paul.

I would think your avenue of redress would be with the retailer you bought the RT from, rather than with Yuasa themselves. And if you are in the US, then the Federal consumer complaints dept would be the place to lodge, see here: **LINK**

You should have a pretty good case armed with the English language brochures that state in plain English that rotary cutting is OK, then their lame excuse that it isnt but they got the translation wrong. Seems pretty cut and dried really.

How hard did you have to wrench on the handle to feed the table around while doing this? Finger pressure? Full hand pressure? Full wrist and elbow pressure? Any harder than you would normally expect to hand feed the milling machine table when making a straight cut? (Though, itseems that an 8mm cutter would snap off if excess pressure were applied.)

Used firm finger pressure but not hard, mainly to overcome the grip of the locking clamps. Slow turning of handwheel and mill at about 600-700 RPM. As you have said, the cutter would have snapped if cutting too hard.

Table was working fine prior to this operation although a drilling operation with clamps locked but could not feel any problems when turning handwheel.