Posted by BillS on August 14, 2014 at 09:27:53:
In Reply to: Re: thread milling posted by NITKHA78 on August 14, 2014 at 03:33:19:
The pictures are good - but I'm not familiar with HMW so we can hope someone else with HMW experience will join in.
since you may be having "part stability" problems, we would like to see additional pictures.
Can you send a closeup of clean, completed part showing (bad) spline teeth?
Also with machine stopped, a closeup of the part mounted in chuck (not running) looking at the cutter in mesh with part?
question 1: Is the hob head set to the angle marked on the cutter?
question 2: If you put a wrench on the part in the chuck and apply firm pressure, is there any backlash or play when you pull or push the wrench? There should be "0" movement if you put a dial at one of the chuck jaws and the base fixed to the machine table. Let us know what your dial shows you for backlash.
Hobbing machines that use a worm and wormgear for final index drive make use of the inability to back drive the
wormgear and a near "0" worm/wormgear backlash adjustment to prevent backlash.
If your index drive "box" has a worm/wormgear, then look for an adjustment for backlash between worm/wormgear.
Or, there might be a "brake" or other mechanism for preventing back drive of the part? In either case, the adjustment must
be carefully made to avoid too much friction and heat.
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