Grizzly H5940 Rotary Table rebuild

[iron man]

Hi I have a Grizzly H5940 Rotary Table that I received as a gift and there was no way I was going to return it so after reading several complaints about this table I decided to tear the table down and go through it to make it work. I could go way over board and bore it install timken bearings but I think it would be better to fix what is there so anyone can make it work good.

The first thing I noticed on the tear down that the steel and cast iron parts are pretty good with some and I do mean Some nice machine work but most of that is cosmetic. The table has no ball or timken bearings in it at all that is OK there seems to be plenty of thrust surface but no brass thrust washers or anything like that. My first concern was when the worm gear is on an excentric so it can be realeased so the table will free wheel that is great as long as when the worm mates with the gear and they line up this one does not the worm gear is to low and the only way to change this is to lower the table and gear assembly. The second problem appeared to be the worm gear looks like it was dropped on the floor from the factory and a couple teeth where slightly damaged along with all the casting sand inside and a lack of grease things where looking dim.

I started by dressing the worm gear the gear is about as hard as my mother in laws heart and a file would barely touch it but I finally got it cleaned up. I then took the housing to the mill and set it up to cut out the lower thrust surface to get better gear alignment. I remove 25 thousands and then I went to lap in the table thrust surface but I did not want to remove any material from the table thrust surface. It was nice and straight with the surface of the table so I use some spray on adhesive and stuck a piece of 400 wet/dry sand paper to the bottom dropped the table back inside the housing and with a drill I lapped in the surface checked it with some blue dye and it turn out shinny and perfect.

After I cleaned everything up I reassembled the table back into the housing reinstalled the worm gear and presto!! smooth as can be. Now it is almost impossible to measure the gear height of the worm without xray vision but as close as I can measure it is in pretty close alignment with the main gear maybe someday I will make a new worm gear for it that is slightly larger in dia. that way the excentric will not have to roll over as far and pull it off center.

Now I cannot reassemble because I want to take some pictures and for the bottom thrust I ordered a needle type thrust bearing the stock method was almost laughable and I will make some changes to the locking devices as well. That is all for tonight the thrust bearing should be here tomorrow and I also going to create a thrust surface up close to the table for more stability.. Ray

 

[iron man]

Well here are some pictures if you look where the caliper is pointing you will see the floor of the casting I removed 25 thousands from and then lapped in the table thrust surface to the upper left. The ring off to the right I machined for a table thrust surface to help keep the table stable.

 

[iron man]

Here is the table with the brass thrust washer installed this will ride on the upper lip on the top of the housing in the upper left corner of the picture. I had to take some very exacting measurement because both thrust surface have to mate at the same time I also took a little off the top lip of the casting to make sure it was flat. A little bluing dye shows they are both making contact.. My needle thrust bearing did not come in today so I will work on more of some of the other irritating features this weekend. Ray

 

[joe_m]

Thanks for the good info. Someday I'll tire of using my grizzly rotary table as a cupholder and this will help guide me through my own rebuild.
Joe

 

[iron man]

Thanks for the good info. Someday I'll tire of using my grizzly rotary table as a cupholder and this will help guide me through my own rebuild.
Joe

Well Joe thats a heavy cup holder there is room inside for all kinds of possibilities I am just doing and easy one right now. Maybe someday I will make a new worm and shaft but if this works good then I may just leave it be.. Ray

 

[iron man]

Here is the stock setup there are two spanner nuts to take up slack in worm gear shaft they are very hard to get just right. The little bit of flat spot left for the adjustable arm leaves alot to be desired everytime I tried to align it with a hole in the disk it would bind because of a lack of support and it was machined so loose it moved around. At this point I was going to start over and cut a new gear and shaft the gear is 8 threads per inch so it was not that hard but then I come upon another idea. Ray

 

[iron man]

Here is the stock setup again not very user friendly. The photo does not show the little 1/8" pin drill and drove into the shaft and ground to a point this was suppose to be for the 10 second knob to drive off. Who ever come up with that dumb idea should have been sent home.

 

[iron man]

This is what I come up with I took a piece of brass and machined a couple flat spots that fit the adjustable arm I then threaded it 12MM 1.5 and drilled in a setscrew. This now tightens up till you get the right amount of thrust and you tighten the setscrew to lock it to the shaft a ring has been machined into the shaft for the setscrew to tight up in. I did lap it in so it aligned with the flat on the shaft.

 

[iron man]

And here is the finished product nice and tight and it works perfect I also cut a 1/8 keyway into the shaft for the knob when the indexing plates are not being used so you have to keep the little key with the knob but no biggy just put it in a zip lock bag and put it away till you need it I still reduced the number of parts. If you are going to do this project have a set of metric dies on hand none of the threads on the shaft where cut to full depth and none where in very good shape.. Till tomorrow.. Ray

 

[iron man]

Well guys I could not help myself I had some brass I had some drill rod I hated the looks of the old gear it was slightly to small in dia. and even with my best efforts still was not making full contact and the threads where cut to wide. So I set in to make a new gear that fit the gear on the table perfectly. I bored it 3/8 and made the new shaft with 1 1/2 thousands press fit I also installed a setscrew but after pressing it on I found that they where not needed extra insurance anyway.