Trying to remove excessive backlash on x-axis

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A few weeks ago I purchased a Grizzly G0619 (SX3) mill. I have been trying to adjust the backlash to ~ .003". I have tightened the cap screws in the half nut to the point where the adjustment section of the half nut is touching the main section nut and I have .019" of backlash. I know if I go any further I will snap the heads off the cap screws. I know I must be doing something wrong. Any help would be much appreciated. I have attached a pic of the half nut as it sits right now with the .019" of backslash. Can anybody tell me what I am doing incorrectly here?


Thanks in advance.

Take Care,

Jim. . .

half nut.jpg
 
I just went thru the manual. Page 27 tells you what to do. You are correct in your nomenclature. One thing I see is that gap. That is not supposed to be there. Part of your problem is there. Get rid of that and I'll bet you are close.

"Billy G"

http://cdn0.grizzly.com/manuals/g0619_m.pdf
 
It looks like you need to make a new nut. If you adjusted it that far and you still have backlash then the thread in the nut was cut WAY too big. Take off the nut, measure it up, put it back together and get to work. Isn't that why we have these machines? :thumbsup:

Tom
 
here is the parts list from grizzly you would have to call to see if it is available but i see a mix up in the list i think they have x and y part numbers reversed see what you think
you could probably make a better one by making the side that adjusts a little thicker so it has more thread surface area.
steve

http://www.grizzly.com/products/g0619/parts
 
HOW DEEP are the threads in the nut cut? I've seen them cut only .015" deep!! Bought a nearly new Enco knee mill years ago,and the lead screws would actually JUMP the threads in the nuts because the nuts were cut so incredibly shallow. They WERE NOT WORN,either. And,the leads crews were METRIC,so there were an annoying several thousandths left over on the dials,making it a huge PITA to space holes several inches apart accurately.I had bought INCH expensive acme rod,and was preparing to make new nuts when a guy came along and bought the machine to repair himself. I could NOT get spare parts from Enco,either. Asian crap is such a gamble.

P.S.: THAT type of adjustable nut is the cheapest and least effective design ever put out. The tilted thread only will touch the lead screw at 1 spot,instead of all the way around,and it will soon wear more. That's the way my Enco was made.
 
george wilson said:
HOW DEEP are the threads in the nut cut? I've seen them cut only .015" deep!! Bought a nearly new Enco knee mill years ago,and the lead screws would actually JUMP the threads in the nuts because the nuts were cut so incredibly shallow. They WERE NOT WORN,either. And,the leads crews were METRIC,so there were an annoying several thousandths left over on the dials,making it a huge PITA to space holes several inches apart accurately.I had bought INCH expensive acme rod,and was preparing to make new nuts when a guy came along and bought the machine to repair himself. I could NOT get spare parts from Enco,either. Asian crap is such a gamble.

P.S.: THAT type of adjustable nut is the cheapest and least effective design ever put out. The tilted thread only will touch the lead screw at 1 spot,instead of all the way around,and it will soon wear more. That's the way my Enco was made.
Click to expand...

I've ordered a new nut. Relatively inexpensive lesson in the greater scheme of things I guess.
 
If the problem IS that the nut is cut way too shallow,and the lead screw is worn much,or is a little undersize for the threaded hole in the nut,the new nut may not do any good. I hope for your sake that this is not the case.

If the new nut still does not solve the problem,you will have to make yourself a new nut,and thread it deep,and make it fit the leads crew properly. I also hope the leads crew is not metric. Do you have left over thousandths on the dial,rather than 1 revolution coming out to an even number? For example,on a Bridgeport,the dials turn .200" per revolution,not something else with 3 or 4 thousandths left over at every turn.
 
george wilson said:
If the problem IS that the nut is cut way too shallow,and the lead screw is worn much,or is a little undersize for the threaded hole in the nut,the new nut may not do any good. I hope for your sake that this is not the case.

If the new nut still does not solve the problem,you will have to make yourself a new nut,and thread it deep,and make it fit the leads crew properly. I also hope the leads crew is not metric. Do you have left over thousandths on the dial,rather than 1 revolution coming out to an even number? For example,on a Bridgeport,the dials turn .200" per revolution,not something else with 3 or 4 thousandths left over at every turn.
Click to expand...

One revolution = .100 with no remainder, but I think the key issue here is that "I do not own a lathe" at this point. We'll see how the new nut goes. If it cuts the backlash down from .025 to ~ .010 I'll be a happy guy.
 
Lucky you have an INCH lead screw!!

I'll tell you how they used to make threads for blacksmith's post vises in the 19th.C.. They'd take a piece of thoroughly ANNEALED iron wire and wrap it in the vise's screw,which could have had square threads or an early Acme type. They'd drill the hole for the nut the size that the screw would just fit through. The wire would have to be of such diameter that when wrapped in the vise screw's thread,it would be flush with the outside diameter of the screw. Careful filing down of extra wire sticking beyond that would work. Then,they'd carefully screw the wire off of the screw,dope it well with flux,and silver solder it into the hole. Be careful to not over do the silver solder so it doesn't block the hole enough to keep the screw from going through.Crude,but effective if you have no lathe. If done well,it would eliminate most backlash,and last until you got a lathe. Takes a lot of heat to heat the whole nut assembly red hot.
 
george wilson said:
Lucky you have an INCH lead screw!!

I'll tell you how they used to make threads for blacksmith's post vises in the 19th.C.. They'd take a piece of thoroughly ANNEALED iron wire and wrap it in the vise's screw,which could have had square threads or an early Acme type. They'd drill the hole for the nut the size that the screw would just fit through. The wire would have to be of such diameter that when wrapped in the vise screw's thread,it would be flush with the outside diameter of the screw. Careful filing down of extra wire sticking beyond that would work. Then,they'd carefully screw the wire off of the screw,dope it well with flux,and silver solder it into the hole. Be careful to not over do the silver solder so it doesn't block the hole enough to keep the screw from going through.Crude,but effective if you have no lathe. If done well,it would eliminate most backlash,and last until you got a lathe. Takes a lot of heat to heat the whole nut assembly red hot.
Click to expand...

That's too funny! :whiteflag:
 
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