New G9729 - Some early issues.

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Diesel Gypsy
Posts: 11
Joined: Mon Feb 01, 2021 12:40 pm

New G9729 - Some early issues.

Post by Diesel Gypsy »

Well, I finally got my Grizzly G9729 lathe delivered, hauled to the basement, set up and running!
I was prepared for a long job of cleaning all the swarth out of it but I was very pleasantly surprised. It was very clean and crap free!
Of course it was slathered down with plenty of grease but none of the filings and chips that I had been led to believe would be there.
Although there were a few funny looking little bits under the cross slide but they weren't chips???

The fit of everything is also a pleasant surprise. Everything fits very precisely. The runout on the 3 jaw chuck, for example, was about 2 tenths!!!

However, not everything was perfect. The first issue I discovered was the pulleys on both the lathe and the mill were TERRIBLE. They looked like they had welding spatter all over them and then coated with a thick coat of black paint. If I had run it like that it would have eaten the belts immediately.
So, a lot of filing and emery cloth finally got them looking a little better.
On the lathe I was able to stick my finger in the little safety switch hole to keep the lathe turning with the door open so I could sand down the pulleys with the other hand but they were sneakier on the mill. You can't run the mill with the cover off!!!! There is an electrical current needed from one post to the other for the mill to run. In order to sand down the pulleys I needed to have the mill running with the cover off so I now have 1 less coat hanger in the closet :-P

So it runs but the next issue was that I needed to cut some metric threads. The chart tells me that I need a 24 tooth gear in D to match up with the 120 tooth gear that is part of the 127 tooth gear. No problem except the 24 tooth gear can't mesh with the 120 tooth gear because the 127 tooth gear hits the shoulder of the 24 tooth gear first, preventing it from meshing with 120 tooth gear.
Has anyone else found this problem?
Anyway, this was easily fixed by switching out the 24 tooth for the 48 tooth and changing the A gear from 36 teeth to 72 teeth. However this won't work for all metric threads but it got me by this time!

Another issue I am having is with the gib adjustment screws for the carriage. They use the (cheap) method of double setscrews. These are very hard to set and quite troublesome. I am thinking of changing them out with some long capscrews and locknuts.
Has anyone got any better ideas? I'm definitely open to suggestion!

I've also found issue with the gib on the cross slide. I like the setup that Torch made for that but I can't understand why they made such a short gib in the first place and expect the adjusting screws to slide across the end of the gib without catching and jamming!

Don't get me wrong though, I love the lathe/mill and, except for these little issues, I am very happy with it!
Torch
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Location: Muskoka

Re: New G9729 - Some early issues.

Post by Torch »

I did long set screws + locknuts for the carriage gibs. Way better.
toddalin
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Re: New G9729 - Some early issues.

Post by toddalin »

No problem running the ShopTask models with the doors/hatches open as there are no electrical "interlocks."

I did make and add table limit switches after the first time I used the power feed and it snapped the spline shaft when the scale on the table hit +4-1/2" even though the table has 11" of travel on the scale. The pointer was that far off.
pete
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Re: New G9729 - Some early issues.

Post by pete »

Fwiw non tapered set screw type gibs have an inherent and built in design flaw. Tapered gibs are always going to be better because there physically locked in place and can't move with the slide due to the two opposing screws, and that's why there used on higher cost machines.But there also a lot more costly to add. Due to frictional drag with the set screw type, the gib tries to move back and forth as the slide moves. Most gibs of that type are partially drilled where the machined points of the set screws touch. That's supposed to and does keep the gib from moving very much, but as the slide moves that gib always try's to follow it so it will also try to move on those screw tips. Then they act like miniature wedges that further tighten your gib adjustment. To compensate you have to run the adjustment a little looser to get a smoothly operating slide and that can have other effects even when the slide isn't being used. Every adjustment position is never really correct nor does it remain stable each time you use that particular slide. So that extra clearance can result in poorer surface finishes. And if it's adjusted too tight, that further self tightening effect ends up in higher wear rates on the dovetails, feed screws and nuts. George Thomas addresses this exact problem in his book The Model Engineers Workshop Manual. And as he mentioned, some or most in his opinion try to adjust there set screw gibs a bit too tight to try and compensate for a too loose and poor surface condition on the part. As he explained it, if the slide is in good condition it should always be smooth and easy to move, yet without any perceptible side to side clearance. A further issue with slides too tight is it doesn't move small amounts when your dialing in that small movement. You end up with a stick/slip situation. The feed screw try's to push against the nut until the pressure builds up to where it overcomes that frictional drag. So the slide doesn't move until you get to that point and it then it generally over shoots what your expecting it to move.

His easy but still a bit touchy to do solution was to drill and ream a single hole through the side of the slide, in the middle of and through the gib itself and just partially into the fixed dovetail on the other side to gain clearance for both the drill and reamer so you get a full clean and reamed hole in the gib. I did mine in the mill, but a drill press would work. I fully tightened those gib screws and that locked the gib in it's working position before drilling and reaming the hole.Then a pin with a sloped end on it's inward face to match the gibs angled face is driven through the side of the slide and into but NOT quite through the gibs face. The pin is made so the end that goes into the gib is a light to medium press fit and the other end that goes through the side of the slide is an extremely close but still sliding fit. I'd guess there's maybe a .0005" clearance on mine. In use that pins the gib from trying to move fore and aft but still allows for future wear and gib re-adjustment. I can adjust the tapered gibs on my mill to much tighter clearances, yet that gib design still allows far smoother movement with no trace of slack than my lathe with it's much less bearing surfaces and weight. I've so far only done my lathes cross slide and there's a definite improvement, so I know it does help.

It's more personal choice than anything, but those straight set screws are good for chewing up your fingers and hands when cleaning the lathe. I replace them with the shortest possible Allen head bolts that still have enough length for future adjustments. An 1/8th of an inch longer is more than ample. If you put .125 thou of wear on your dovetail and gib, then running out of adjustment is the least of your problems. :-) The locking nuts are obviously reused as well.
Diesel Gypsy
Posts: 11
Joined: Mon Feb 01, 2021 12:40 pm

Re: New G9729 - Some early issues.

Post by Diesel Gypsy »

Thanks Pete, some good ideas there. I wish it had tapered gibs! My larger Butler lathe has all tapered gibs and it's slides all work smoothly with very little play.

On this little Grizzly though, their design could have been better. The carriage gib is designed to slide against the dovetail and is adjusted with 2 setscrews from behind the gib. Simple enough right? But then then their idea to hold those setscrews in place was to put another set of setscrews in behind the first set. This pushes the slack out of the first setscrews effectively locking the carriage. Obviously this is unworkable and I simply replaced the setscrews with long capscrews (8mm x 100mm) to bring it out to the outside of the apron and used locknuts to hold it in place.

The cross slide however is not so simple. It's gib is locked onto the inside of the dovetail, on the carriage side, and the setscrew adjuster/locks are on the cross slide. This means that it is only the end of the setscrew that slides along the gib that holds the cross slide tight. To make matters worse, the gib is not long enough for the cross slide travel for 1 setscrew to do the job so there are 2 but they have to cross over the end of the gib to complete the travel. Kind of like a relay race where one runner carries the baton for the first part of the race and then hands it off to the next runner to carry it further. This may work in a relay race but it certainly puzzles me why they would think it would work on a lathe! Then, their adjustment consists of those 2 setscrews with floppy handles attached and no locking mechanism at all.

Torch made a good system of adjusting/locking setscrews but it is still just sliding the setscrew against the gib. Why would they bother to put a gib in there at all if it is just going to sit there and not slide and put all the wear on the end of the setscrew anyway?

So far the only solution I have thought of is replacing the gib with a longer gib which would be attached to the cross slide side and some more setscrews to hold it.

Has anyone else found a simple way to fix this? I'd sure like to know!
Torch
Posts: 1684
Joined: Wed Mar 17, 2010 7:58 am
Location: Muskoka

Re: New G9729 - Some early issues.

Post by Torch »

Mine has a tapered gib on the cross slide. Look for adjustment screws on either end of the gib. The lock screws are just for locking the cross slide, not adjusting the gib.
Diesel Gypsy
Posts: 11
Joined: Mon Feb 01, 2021 12:40 pm

Re: New G9729 - Some early issues.

Post by Diesel Gypsy »

From the manual:
Cross-slide Gib: The gib on the cross-slide is
adjusted by tightening or loosening the 2 wing
bolts located on the right hand side of the slide
(see Figure 74). These will also serve as table
locks.

I would send a picture (Fig 74) but I guess I don't know how to get a picture on here :oops:
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Harold_V
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Re: New G9729 - Some early issues.

Post by Harold_V »

Diesel Gypsy wrote: Mon Mar 15, 2021 2:27 pm I would send a picture (Fig 74) but I guess I don't know how to get a picture on here :oops:
To post an image one can NOT use the Quick Response button. Post Reply button must be selected.
With the proper page opened, images are posted as attachments. Follow the instructions on that page.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
Torch
Posts: 1684
Joined: Wed Mar 17, 2010 7:58 am
Location: Muskoka

Re: New G9729 - Some early issues.

Post by Torch »

Diesel Gypsy wrote: Mon Mar 15, 2021 2:27 pm From the manual:
Cross-slide Gib: The gib on the cross-slide is
adjusted by tightening or loosening the 2 wing
bolts located on the right hand side of the slide
(see Figure 74). These will also serve as table
locks.

I would send a picture (Fig 74) but I guess I don't know how to get a picture on here :oops:
That is an error in the manual. Look at page 66 of the manual (at least, that's the page on the version I downloaded from Grizzly). "G9729 Cross slide assembly". Part number 726 ("Adjust screw") and 727 (Table gib). There's actually a second 726 at the back of the table, but not shown on the diagram for some reason.

Note how the front of the gib is notched. The head of the front adjust screw is captured by the notch. Loosen the rear screw, then use the front screw to set the gib. Always tighten to the adjustment point -- if you go too tight, then back the screw off to pull the gib back a bit and try again. When satisfied, use the rear screw to lock the gib in place.

Those screws on the side are just table locks. And yes, my little mod to work both at the same time is the cat's meow. Should have been that way from the factory, IMHO. ;-)
Diesel Gypsy
Posts: 11
Joined: Mon Feb 01, 2021 12:40 pm

Re: New G9729 - Some early issues.

Post by Diesel Gypsy »

Torch, I stand corrected! I pulled the cross slide off again and discovered that it is indeed a very slightly tapered gib!
However this brings with it another problem, I can now tighten the far side but I still have about 18 thou slop in the close side!
So now I am wondering if I should start monkeying around with the gib or see what Grizzly might suggest since it is on warranty.
Torch
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Joined: Wed Mar 17, 2010 7:58 am
Location: Muskoka

Re: New G9729 - Some early issues.

Post by Torch »

Definitely talk to Grizzly. The saddle should have a matching taper so the outer face of the gib is parallel to the opposite dovetail. It almost sounds like the gib is in backwards, but the notch should be on the lower front.
Diesel Gypsy
Posts: 11
Joined: Mon Feb 01, 2021 12:40 pm

Re: New G9729 - Some early issues.

Post by Diesel Gypsy »

The gib is in the right way (pretty much can't go any other way) so either the gib or the saddle must be ground wrong?
Grizzly is going to get one of their techs to call me tomorrow.
I'll let you know how it goes.
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