Slightly O/T question about a Lathe repair

Hey Guys,
This is slightly off topic, but since I usually only visit the gunsmithing area, I had hopes of not getting my question blown off in the regular forum areas.

I have a Grizzly 14x40 lathe, and had a part of the cross slide casting break on me. I was parting off a piece of stainless to practice barrel threading, and had the parting blade tip break which caused the parting blade to dive under the bar, and torquing the compound up, snapping the casted ring area that holds the clamp down screws of the compound to the cross slide. Ok, my fault for not being careful, but called Grizzly and they promptly shipped out a new Cross slide. The part I didn't think about, is how they fit the gibs to each cross slide/apron pair. After getting the new slide in, the original gib I have won't fully slide down into the slot, and after looking at it, it had been scraped in the fitting process. I don't have the capability to hand scrape, or to have one edge precision ground down, so I'm looking for opinions on where to go.

The gib is ~13" long, and sticks out about 1.5" too far. Part of me says, well, just shorten it, it would have contact over about 11 of 13", and since I am a very light personal user, it will never cause any problems. But another part of me thinks that maybe it won't have a very nice fit either and may over time wear the apron unevenly, but again, I'm a very light user. With the gib in tight, there is definitely no play anywhere, and maybe just shortening the gib down would work?

Thoughts?

Thanks,
Travis

Please be careful talking about the "green machine company", as home shop grade machinery/tooling is frowned upon here.
You must have been really rough parting, try using a steady or follower rest next time.....
People (including me) shorten gibs when they get work so they can be tightened farther, you have to do that on bridgeports and other mills because of the chip wiper will get smashed if the gib is too long and you tighten it forcing it into the weak chip wiper casting, and I assume thays the same way for lathes. Mine was broke that way before I got it.
It's good practice to not only shorten it but shorten it .25" below the casting to compensate for future wear, which happens quickly on lathes without hardened ways.

Been there done that. I broke a cross slide the exact same way, learned my lesson in machining 101. Without seeing it and based on your descriptiion. Your gib can be shortened and then use (make) a brass part to use on the back end of the gib. Not really a good description but use your head, think it through, you will get the idea. If you are a machinist you will have no problem.

Thanks for the response, Spyderedge. Frowning upon the asian machines was why I didn't post this in the general forum. But I primarily use this for personal use for gunsmithing things, and I'm sure there are many other gunsmithers here who have the asian machines as well!

I guess the main concern is that since the gib was not carefully fitted to match this cross slide (not sure how carefully the original one was fitted either?) if the fit isn't really close, would this harm it over time? I guess I could put some layout dye on it and check the fit. If it has good solid contact, maybe that's the way to go, but if not, I'm not sure how to fix that myself. Thoughts?

Thanks for that keydiver, I hadn't thought about the effect of the back screw if shortened. Would have been obvious though, need some way to apply back pressure to the gib, and that will be easy enough to fix.

tmccoy said:

Thanks for the response, Spyderedge. Frowning upon the asian machines was why I didn't post this in the general forum. But I primarily use this for personal use for gunsmithing things, and I'm sure there are many other gunsmithers here who have the asian machines as well!

I guess the main concern is that since the gib was not carefully fitted to match this cross slide (not sure how carefully the original one was fitted either?) if the fit isn't really close, would this harm it over time? I guess I could put some layout dye on it and check the fit. If it has good solid contact, maybe that's the way to go, but if not, I'm not sure how to fix that myself. Thoughts?

Click to expand...

I'm not frowning on Asian machines, I've seen them do some incredible work and even the little 7x9" mini lathes are quite capable in the hands of many.
Gibs should always be scraped to fit the ways by rubbing the ways with high spot (prussian) blue, then inserting the gib and tightening it just snug. Then remove it and you should see some blue on parts of the gib. Proceed to scrape them away with a machinists hand scraper (enco and grizzly has sets for cheap if you don't want to invest in a carbide scraper) then repeat the process untill you have many bearing spots and at least 60% contact.
Then in time the gib will wear to fit the ways and everything will be fine.

tmccoy said:

Thanks for that keydiver, I hadn't thought about the effect of the back screw if shortened. Would have been obvious though, need some way to apply back pressure to the gib, and that will be easy enough to fix.

Click to expand...

If I were you I would rescrape the gib for the proper fit, you will be surprised how fast it will go. You can use black magic marker instead of Prussian blue, and for the scraper you can use a 10" file with the end ground to a slight convex radius. Blacken the gib with the marker and install it, then tap it in deeper with a plastic mallet. Remove the gib and scrape the wear area's where it rubbed the black away and repeat until you get the desired depth.

paracongo308 said:

If I were you I would rescrape the gib for the proper fit, you will be surprised how fast it will go. You can use black magic marker instead of Prussian blue, and for the scraper you can use a 10" file with the end ground to a slight convex radius. Blacken the gib with the marker and install it, then tap it in deeper with a plastic mallet. Remove the gib and scrape the wear area's where it rubbed the black away and repeat until you get the desired depth.

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Magic marker is too thick to use as a marking medium and dries far too fast. Blue oil paint works though.
As for a file scraper, files are only case hardened meaning only the outside is hard and the inside or core is softer then the outside. I've already tried that one

Some chinese files may be casehardened... Never heard of a case hardened file.. There are some forms of flexible files out there, which must have a softer core though..

Every file I have ever broken (usually to shorten), was clearly through hardened.

I have made some quicky scrapers out of files before. You must not overheat file while grinding to shape..

That is critical, otherwise you anneal (soften) the scraping edge..

The 14 40 class of machines I believe are OK to speak about... Site owner put a ~4000.00 new price, on the cutoff from home shop stuff.. Green G's are well over that...

Well, after considering all the comments and carefully checking things, it was much easier than first expected. As the gib had already been hand scraped to fit the apron, this fit was unchanged. I had only changed out the cross slide which does not move against the gib. I reconfirmed the fit contact all around and had full contact everywhere, so I was able to just easily shorten up the gib to fit and it looks like I'm good to go. Thanks again for all the comments.

Travis

Spyderedge said:

Magic marker is too thick to use as a marking medium and dries far too fast. Blue oil paint works though.
As for a file scraper, files are only case hardened meaning only the outside is hard and the inside or core is softer then the outside. I've already tried that one

Click to expand...

A magic marker will put a coating on any surface less then 1/2 of what Prussian blue would. I worked at fitting for 44 years before retiring in the automotive die building trade and went through several gallons of Prussian blue. as for case hardened files, never heard of one. We only used Nicholson files made in the USA. Just for the hell of it, take a flat piece of metal and measure the thickness then blacken it with magic marker and measure again.

Regarding the discussion of non-industrial lathes on PM, I do not enforce that rule in the Gunsmithing Forum because that class of machine is commonly used in this trade.

paracongo308 said:

A magic marker will put a coating on any surface less then 1/2 of what Prussian blue would. I worked at fitting for 44 years before retiring in the automotive die building trade and went through several gallons of Prussian blue. as for case hardened files, never heard of one. We only used Nicholson files made in the USA. Just for the hell of it, take a flat piece of metal and measure the thickness then blacken it with magic marker and measure again.

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Hey Paracongo and Tmccoy....This guy is out of his league on this site and dispenses all kinds of B.S. advice. He's trying to fit in but the home sites are better suited for his experience level. Sorry,just an observation.

Travis,
Look at Frank J. Hoose's site, there's some writing about getting gibs right, as I recall it.
Regards,
Max

omrc7771 said:

Hey Paracongo and Tmccoy....This guy is out of his league on this site and dispenses all kinds of B.S. advice. He's trying to fit in but the home sites are better suited for his experience level. Sorry,just an observation.

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Great thing about the internet, we all got opinions. I have no dog in this fight, just sayin' he said his opinion. The poster can pick and choose what he chooses to believe. I have been tearing (meant cutting) schtuff up for a kajillion years and have found a sharpie to lay a thinner film than dykem. As said, just my feebile (sp) opinion

Spyderedge said:

Magic marker is too thick to use as a marking medium and dries far too fast. Blue oil paint works though.
As for a file scraper, files are only case hardened meaning only the outside is hard and the inside or core is softer then the outside. I've already tried that one

Click to expand...

Huh???

Magic Marker works perfectly fine as a marking fluid -- that's what it is. It also works very good as a layout marker where it is removed by contact. Dykem or other layout fluids will transfer better than MM and are mostly better where fit is to be indicated. I think MM gives me a little better indication in grinding applications.

It is sometimes questionable as to how files are made today. That being said, I have made knives from worn out Nicholsen and Grobet files and they were hard to the edge. I have also snapped a Grobet (note to self, there is a reason they call it a file not a lever) and it sure as hell snapped like it was hard through.

I guess for mass market crap files, they could case harden them.

Art

Case hardening steel is usually very low carbon steel, in order to infuse carbon on the outside for hardness, and leave a softer tough core. Any quality file I ever ran across was made from a higher carbon steel that will through harden when heat treating. I also discovered early on not to pry with them.
James