Way Repairs To A Large Mill

S

Str8jacket

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I am currently in the throws of a complete gear box / knee rebuild of my universal. I have had to completely remove the bed and cross saddle and the pivot saddle, if thats the correct terminology. I never wanted to strip it but in its previous life it has had some not so good repairs and in all honesty im lucky it didnt launch the entire gear box out the side. So after repairing some shafts and replacing the bearings im going to put this giant rubix cube back together.
But in the process of stripping it i have found some damage to the ways from blocked oil holes and it has picked up and gouged the bed. I have a not so precision straight edge and it looks good, i am waiting on 2 new proper precision straight edges to arrive to check thoroughly. I have also ordered a 400mm x 400mm cast iron surface plate. My question is what is the best way to repair the gouges and remove any high spots with out affecting the accuracy of the mill? I have no scraping experience and tbo i have no immediate desire to start, i want to use the mill not work on it. If the ways arent worn badly other than the gouge marks, any suggestions on a repair?

Thanks Str8
 
You are not going to learn how to repair and recondition a milling machine from a couple paragraphs on this forum. It really takes an apprenticeship and lots of practice under the supervision of experts. The book Machine Tool Reconditioning, by Connelly, is a great place to start. It is considered to be the bible on scraping. The book sells for about $100, but is a free download on this forum:
http://www.hobby-machinist.com/threads/connelly-on-machine-tool-reconditioning.41802/

I don't know what type of straightedges and CI surface plate you have coming, but to be usable for spotting the ways and other surfaces of your mill they need to be the correct type, and will need to be scraped in to a very high tolerance, not something you will be able to do on your first or tenth scraping job.

In my opinion, the first rule of working on old machines is "First cause no harm." A poor approach from misunderstanding the job and not having the skills and tools to do it correctly will quite possibly make the machine scrap metal for all practical purposes. Don't be in a big hurry, and educate yourself well before you start.

Don't get me wrong, I am not trying to be a downer here, and I would really love to see your machine put back to it's former glory, but please first make sure you know what you are getting yourself into before attacking the machine with a scraper and straightedge...
 
Can you post some pictures of the damaged areas for a start?

My immediate response is to get you a oilstone, like a 2 x 6 size one, and some mineral spirits. Get you a shallow pan to pour some mineral spirits into and submerge the oil stone. Take this oil stone and start honing the damaged areas to remove any high spots. You will find out quickly how worn the ways are. Don't get aggressive, just enough to remove high spots. Take your time and pay attention how the honing stone reacts. Keep the stone saturated with mineral spirits. If it's a smooth action once the high spots are removed, you got it done. And probably don't have much wear. If the action continues to be rough and does not smooth out over a short period of time of honing, might as well stop. You have to decide if you want to recondition the ways at this point or just go back together and leave it as is.

Straight edges will help, if they are of the "camel back" type. If it's just a precision ground type, its not going to help you in re-scraping your ways. About all they will help with is determining how much wear you have by using feeler gages. Get you a assortment of feelers from .001" all the way up to around .015" in thickness. My popular one is a .001" thick. If you cannot work it under the straight edge, I call it good. If it goes in certain areas, then start increasing the feeler thickness until you get one that will not go. The one before the last one tried will be the amount of wear you have. Then from that you can determine the method of repairing the ways. Map out the locations of the most wear, this will determine a approach to take to repair. Report back to us and we'll try to help you out.
 
Thanks for the suggestions.
Bob, i did scraping 20 odd years ago on a 2in x 1in block as an apprentice, i have no intention of going any where near this thing with a scraper! It would be 3 times the size of a bridgeport.
I bought the straght edges mainly to assess whether or not the mill was stuffed or not. As it happens they arrived yesterday and i had a very quick look with a light behind and it doesnt look terrible, a very small strip just visible on one or 2 sections, i will check properly with feeler guages asap. I did gently stone the high spots on one section as you suggested 4gsr already but got scared!
Im not looking to bring this back to any former glory, i dont it had any! Its not a collector item its a work horse, any money spent from here on will be lost. So im minimizing my total outlay.
 
OK, good luck with it! A big universal mill can do a lot of heavy work and make a mountain of chips. A year ago I tried to sell an old (1920's-1930's?) K&T 2B for a friend, no takers at any price. It also had a large Gorton vertical head that was adapted to the overarms and a bunch of B&S taper tooling, guessing #12 for the K&T and #10 for the Gorton head.
 
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Well I've have fully stripped the knee and table and have started to check with a straight edge and feeler guages.
The Z dove tail ways look rough but when checked I couldn't get my .002in feeler in anywhere.
20160624_173924.jpg 20160624_173932.jpg

Not sure on the best way to clean the rusty mungey bits up?
 
The cross slide has some scoured marks but can't fit my feeler guages in anywhere. I don't have one smaller than 2 thou though. I have started to touch up the rough bits with a soft stone
20160624_173956.jpg 20160624_174030.jpg
 
The table slide is the worst. I think it would have .003in of wear on the front right edge. You can see it where the score marks are.
20160624_174040.jpg 20160624_174045.jpg
Don't think there is much to be done about it but clean the rough stuff. Can't afford a shop to repair it..
 
You may find that by the time you get everything well cleaned, touched up, and adjusted that you will be fine. I've been keeping an eye out for something that size for resurfacing engine blocks. Cheers, Mike
 
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