grizzly gunsmith lathe tail stock won't lock tight.

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AllenH59
Posts: 479
Joined: Wed Mar 16, 2011 1:26 pm
Location: Prince George BC Canada

Re: grizzly gunsmith lathe tail stock won't lock tight.

Post by AllenH59 »

Pete: It turns out that they are sending the lower casting for the tailstock, not a complete one. Yes, that is a lot of money here in Canada for a lathe that is junk when it arrives. No doubt he bought that lathe because it had the "gunsmith" status. They ordered one from China, and god knows how long it will take. I also doubt their quality control abilities to grind the new lower casting to a point that vertical centering will be dead on. While I am not a machinist, I would think that achieving contact area is a pretty basic thing at the factory, and they would check to see how much contact they had, and have a minimum spec... I have lots of stuff made in China, and some of it is pretty good.
pete
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Joined: Tue Feb 10, 2009 6:04 am

Re: grizzly gunsmith lathe tail stock won't lock tight.

Post by pete »

I guess maybe expecting a whole new tail stock top to bottom would be pushing things. But imo not out of the question given it's so called build up in the catalog and on line web page about it being something of much better quality. At that extra price for the lathe then Grizzly should have just told the factory to replace the whole thing at there expense. At one time Grizzly had / may still have? there own staff in some of the factory's building Grizzly machines. Either they need to start doing so again or jack up the people that are already there. One problem with the tail stock way's and being not anything close to the surface contact I'd almost pass it off as a missed quality control check, that far too undersized locking plate say's other wise to me. But it still makes one wonder just how often parts are being checked as they come off a machine as each operation is completed. Yes casting can and do warp, if that was the cause then odd how all 4 outside corners were warped evenly enough so just those areas touched well enough no rocking happened. More likely, hard, heavy surface grinding without enough or any coolant, or dull wheel that built up enough heat in the part to make it concave after it cooled down. To me that say's corners are being cut on the shop floor, and if there was any quality control there not doing there jobs either. I'd maybe expect some of that with a Harbor Freight level of machine, but certainly not from Grizzly for one like this and it's price. I'd be interested in hearing how well the new part matches for getting the tail stocks C/L correct if you find out.
AllenH59
Posts: 479
Joined: Wed Mar 16, 2011 1:26 pm
Location: Prince George BC Canada

Re: grizzly gunsmith lathe tail stock won't lock tight.

Post by AllenH59 »

Well, the lower casting came... We assembled it, cleaned the bottom of it with brake clean, cleaned the ways with brake clean, cleaned the anchor block and the underside of the ways with brake clean. We adjusted the position of the cam so that it locks at the very top of the stroke. This one will lock at 120 ft lbs of torque.. We set it up, with a 24 inch long piece and a sharp tool, and we adjusted the tailstock to achieve .002" of taper in 24". The cam feels ok.. not like it is about to break, although it will be a hell of a surprise when it does, I guess we will be making one at my shop.. Now I am thinking about cross hatching the surface under the ways to give it better purchase to lock... What do you guys think?
pete
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Joined: Tue Feb 10, 2009 6:04 am

Re: grizzly gunsmith lathe tail stock won't lock tight.

Post by pete »

I can't speak for that model of lathe, but with the 3 lathes I do have experience with that bottom guideway the lower block tightens up against isn't as well ground as the top way surfaces are. There probably not all that smooth to begin with on that lathe. Removing material by cross hatching it will give even more room for trash and oil to collect, plus it further reduces the surface area. That might end up making things worse instead of better. 120 ft lbs ought to be ample to solidly lock that tail stock down against any sane size of drill being used that I can think of. The coefficient of friction isn't given for steel against cast iron here https://www.engineeringtoolbox.com/fric ... d_778.html Steel on steel was the closest I could find. And a cast iron and steel combination is pretty slippery, much more than steel on steel. As the numbers show adding any oil at all the numbers drop way down. Cross hatching those guideways is just about impossible to change later. If it didn't work, then what?

They slather these machine tools with lots of anti rust preservative at the factory. It does what it's supposed to, but are you sure that's all been cleaned out? I use solvent to help dissolve and wash it all out, then to be sure I like to use CRC electrical contact cleaner. That will wash out anything left. If there's any of that preservative left it might be preventing that block from fully seating against the bottom bed ways.
AllenH59
Posts: 479
Joined: Wed Mar 16, 2011 1:26 pm
Location: Prince George BC Canada

Re: grizzly gunsmith lathe tail stock won't lock tight.

Post by AllenH59 »

We have cleaned everything with both brake clean and acetone.. If this is pilot error, I have no idea what it might be.
John Evans
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Joined: Tue Jan 20, 2009 9:33 pm
Location: Phoenix ,AZ

Re: grizzly gunsmith lathe tail stock won't lock tight.

Post by John Evans »

Well I have a Chinese 12X36 and have been around a lot of that type lathe. Before he closed his shop my machine dealer friend sold 6 or so of the "Shop Fox" brand [Grizzlies other label] and I assembled everyone for him. Did NOT see any issue with locking the TS ,they too had the 1/2 Sq. drive should you want to use a torque wrench. I NEVER needed anything like that much force to firmly lock the TS. Try adjusting the bolt so the cam locks at about 2/3 stroke. My lathe locked solid the handle is at about 11 o'clock. Even punching a 1" hole with 1/4 pilot never need more that a firm slap with my hand to lock solid ,no provision for a wrench fitted OR needed !!
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AllenH59
Posts: 479
Joined: Wed Mar 16, 2011 1:26 pm
Location: Prince George BC Canada

Re: grizzly gunsmith lathe tail stock won't lock tight.

Post by AllenH59 »

John Evans: We tried it at a few different positions, and worked best at just before the apex, which is where physics would say the rotation of the cam would produce the most force. We made another anchor block out of a piece of 1" plate, which fit much better but made no difference.We tried the factory block with the new lower casting, and it was a little better but not good enough. The one we made is longer than the original, and I have considered cutting it to the same length, but it works about the same as the original. We have cleaned with brake clean and acetone. We have scrubbed the bottom where the anchor block runs and we are sure it is clean. We can make the lathe run reasonably accurate, we stopped fooling around at .002" diameter in 9", we could have done better, but we were working on a piece of scrap, and there was no value in getting it closer. we did this by adjusting the cross slide in the tail stock. If you or anyone else can come up with a suggestion and an explanation as to why it will work I am listening.
John Evans
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Joined: Tue Jan 20, 2009 9:33 pm
Location: Phoenix ,AZ

Re: grizzly gunsmith lathe tail stock won't lock tight.

Post by John Evans »

Well diagnosing at a distance is tough ! Have you tried bluing up the clamp piece and trying the fit to the bottom of the bed? Only 2 things now come to mind is the bed clamping surface is not parallel to the upper surface or that surface is not very smooth. like I said blue it up and see how good the fit is.
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pete
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Joined: Tue Feb 10, 2009 6:04 am

Re: grizzly gunsmith lathe tail stock won't lock tight.

Post by pete »

I'd start with what John suggested, but the only other thing it might? possibly be is check the clearances within the tail stock casting for the locking assembly. If there's not enough for the linkage to operate freely it could be binding up and preventing the clamping force from being fully utilized. I'd fully agree something isn't right for sure, but at least there's only a very few things that can cause what your seeing Allen. By now shiny spots on the parts or paint removed should instantly tell you if any of those parts are touching where they shouldn't be.
Rwilliams
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Location: Central California

Re: grizzly gunsmith lathe tail stock won't lock tight.

Post by Rwilliams »

I found the same style of small anchor block located under the tailstock of my new Jet gear head 1340 lathe when it arrived. Same anchor block was used for the steady rest no less. The anchor block was perhaps half the length of the tailstock base and when tight, would allow the tailstock to move with too much drilling pressure. I was not impressed. Rather than even try to resolve the problem with the dealer or factory, it was easy enough to make up a nice wood pattern. The pattern was designed to give maximum size possible under the tailstock and contact with the lathe ways. Once cast and machined to fit far better, the new anchor block was given a new oversized washer to spread the clamping pressure more evenly. The contact surface area with the ways was stoned with fine stones and some oil until the tool marks were all removed. Made the surface look like it had been ground. With the cam adjusted for the new parts, the tailstock is now rock solid like it should have been from the factory. Have considered having the pattern cast again to make a second clamp block to upgrade the steady rest support.

The other day I was using the steady rest for a big job at work. The Axelson lathe is a real brute from perhaps the early 1950 era and rock solid. I noted the size of the clamp block for the Axelson steady rest was massive. No way was the steady rest going to move at all once clamped down. It appeared to be a casting that was easily two inches square or more and about 10 inches across the ways. I did stone the clamp block way contact surfaces a bit to clean them up. Abuse in the past had not been kind to the well used machine tool.
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