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Neil Jones
04-10-2009, 01:38 AM
If I take a scrapping class would I gain the knowledge necessary to scrape a worn out surface grinder back to new spec?

Is a Harig 612 a good grinder to start with since they seem to still sell many of the parts needed?

How difficult is it to learn how to apply Turcite to the saddle and scrape it?

What are tools I'd need to rebuild a worn out surface grinder?

Is there a market for quality rebuilt surface grinders?

easymike29
04-10-2009, 08:54 AM
The Harig's I remember had hardened and ground ways.
Gene

Neil Jones
04-10-2009, 09:29 AM
The Harig's I remember had hardened and ground ways.
Gene

http://www.harigproducts.com/rebuild.html

"All way surfaces are reground and prepared for scraping."

moldmonkey
04-10-2009, 10:37 AM
As far as a market, there isn't much of one for small manual grinders as most shops already have one or want automatic ones.
HSM would be the market and they are notoriously cheap.:)

lazlo
04-10-2009, 10:52 AM
I have a Harig Super6x12. It has the sliding prismatic/flat ways. I don't know if they're hardened, but the Harig ways are ground and then flaked (so I'd guess they're not hard). You can also get the Harigs with Turcite slideways and roller bearing ways.

It's a really simple machine. If you were going to rebuild the saddle/table, I'd recommend going the Turcite route, since scraping hardened ways is really difficult, although Harry Beckley has proven that it's possible.

Scraping the Z column would be a lot more challenging -- it's a trussed box structure, and the slideways tilt inward at about 60 degrees.

Bruce Griffing
04-10-2009, 11:14 AM
I would not make the effort for a manual machine. If it feeds automatically, then it may be worth the effort.

Mcruff
04-10-2009, 01:22 PM
The Harig 612 is a fine surface grinder. They are still in decent demand in small mold shops that do precision molds. I have worked in 3 different mold shops that had 10-15 each or more that were ran all day long. I have spent literally 1000's of hours grinding small inserts with one.
They used to come with hardened tool steel ways, Teflon coated ways (avoid) and my favorite hard chromed ways, when new the chromed ones are the hardest to break in. They have offered roller tables for years bu they are not that common in my experience. When I had my shop back in the early 90's we had 2 of the tool steel ways and an Okamoto 7x14 ball bearing grinder.
You really need to see what kind of ways it has on it, they do offer cast iron ways but that doesn't mean the grinder you have has them, I personally in 29 years of grinding have never run a Harig with just straight cast iron ways.

wierdscience
04-10-2009, 02:10 PM
Anything can be rebuilt,only question is will it be worth doing?

For what I have seen of surface grinders,for the ways to be wornout at that point the rest of the machine is shot too.

There is limited market for small manual surface grinders.Brandnew import virgins can be had for $2500 or less ad used American 6x12 sit in inventory for years.We have two parked at work now taking up floor space.Too good to scrap,too little demand to sell.

Neil Jones
04-10-2009, 07:15 PM
I have a Harig Super6x12. It has the sliding prismatic/flat ways. I don't know if they're hardened, but the Harig ways are ground and then flaked (so I'd guess they're not hard). You can also get the Harigs with Turcite slideways and roller bearing ways.

It's a really simple machine. If you were going to rebuild the saddle/table, I'd recommend going the Turcite route, since scraping hardened ways is really difficult, although Harry Beckley has proven that it's possible.

Scraping the Z column would be a lot more challenging -- it's a trussed box structure, and the slideways tilt inward at about 60 degrees.


I'm glad to hear "it's a really simple machine" as this would be my first machine rebuilding project. I'm thinking of buying a junk Harig to pull apart and practice on to see if I can rebuild it.


Turcite seems to make sense as this appears to be the way most modern machines are now made. How do you apply Turcite to the ways?

What tools would I need to purchase or make to check the saddle/table as I scrape it? What tools would I need to scrape the Z column? Could the Z column be ground by someone who does this kind of grinding and then maybe I could scrape the head to the column?

Neil Jones
04-10-2009, 07:20 PM
Anything can be rebuilt,only question is will it be worth doing?



That would be the purpose of why I started this thread.




For what I have seen of surface grinders,for the ways to be wornout at that point the rest of the machine is shot too.



Agree and I expect that.




Brandnew import virgins can be had for $2500 or less



At that price they are probably garbage that won't grind to .0001 and if by some miracle they do they won't hold that tolerance for long.

Mcruff
04-10-2009, 07:52 PM
As I stated above not all Harigs have iron ways, you need to check first. They came with iron ways, tool steel ways, Hard chromed ways and teflon coated, not to mention the ball ways. Most all of them I have seen built since around 1970-72 have been hard chromed or tool steel. I have personally never seen a Harig with staright iron ways. I'm sure there out there though.

Neil Jones
04-10-2009, 08:45 PM
As I stated above not all Harigs have iron ways, you need to check first. They came with iron ways, tool steel ways, Hard chromed ways and teflon coated, not to mention the ball ways. Most all of them I have seen built since around 1970-72 have been hard chromed or tool steel. I have personally never seen a Harig with staright iron ways. I'm sure there out there though.

So if they are tool steel they can only be ground? If they are hard chromed the chrome must be removed before they can be scraped? If they are teflon coated the teflon must be replaced?

beckley23
04-10-2009, 10:46 PM
If you take a scraping class, you will learn the basics of scraping, you will not learn how to scrape a machine in for alignment.
Scraping for alignment is a logical building block type sequence of scraping the various members for alignment. I strongly recommend that you obtain a copy of Edward Connelly's book "Machine Tool Reconditioning". It is advertised in HSM.
To get an idea of what is involved, you should read the following topic ;
http://www.practicalmachinist.com/vb/showthread.php?t=146913
This is not for the faint of heart, it is a long, time consuming, and very boring project.
If you are starting from nothing, this can get pricey.
Harry

chrsbrbnk
04-11-2009, 12:53 AM
I second for getting the book even if you don't rebuild one its a good insight into the process or even looking for a used machine

DR
04-11-2009, 12:36 PM
.................................................. ........

Is there a market for quality rebuilt surface grinders?

Neil,

I like your enthusiasm for this project. Yes, I believe there is a market for quality rebuilds.

A few points from someone in the business of precision machining.

I avoid like the plague "rebuilt" equipment, unless it's done by a shop to factory new standards. That would include a detailed inspection report on the machine, squareness of column to table, flatness of table movement, full inspection report of the downfeed screw and so on and so on. The inspection itself would require an extensive assortment of expensive inspection equipment.

Then there's the spindle to deal with.

I'd expect a warranty approaching what the factory gives on new machines.

I don't want to discourage you, so I suggest you buy one and get started. If nothing else, it'll be a valuable learning experience.

Scishopguy
04-11-2009, 12:59 PM
I am surprised that nobody has mentioned the spindle. I think you will find that it is the "high dollar" item and the parts are pretty expensive too. Back in the early 80's we acquired a DoAll surface grinder with a hydraulic feed system. The machine had a Parker spindle that we priced a factory rebuild on at $3000. The bearings were pretty expensive if you could get exact replacements.

Neil Jones
04-11-2009, 08:01 PM
If you take a scraping class, you will learn the basics of scraping, you will not learn how to scrape a machine in for alignment.
Scraping for alignment is a logical building block type sequence of scraping the various members for alignment. I strongly recommend that you obtain a copy of Edward Connelly's book "Machine Tool Reconditioning". It is advertised in HSM.


I have had this book for years but I'm just to the point where I can read and comprehend some/most of it. It took a long time to get the mechanical background to feel comfortable enough. I recently started buying tools I know I will need such as a Starrett 199 Level. It would be very helpful if you could list other tools that someone as experienced as you knows I will need for this job.




To get an idea of what is involved, you should read the following topic ;
http://www.practicalmachinist.com/vb/showthread.php?t=146913
This is not for the faint of heart, it is a long, time consuming, and very boring project.



It's taken me many years to become slightly mechanical. I'm sure it will take years to learn what I'm doing rebuilding this grinder and I'm sure I'll lose my ass on it.






If you are starting from nothing, this can get pricey.
Harry



I am.

Neil Jones
04-11-2009, 08:06 PM
I am surprised that nobody has mentioned the spindle. I think you will find that it is the "high dollar" item and the parts are pretty expensive too. Back in the early 80's we acquired a DoAll surface grinder with a hydraulic feed system. The machine had a Parker spindle that we priced a factory rebuild on at $3000. The bearings were pretty expensive if you could get exact replacements.

The price list I have (retail) from Harig shows the bearings (I guess there are two needed) to be aprox $900 and $625.

The oil pump ain't cheap either.

Neil Jones
04-11-2009, 08:12 PM
Neil,

I like your enthusiasm for this project. Yes, I believe there is a market for quality rebuilds.

A few points from someone in the business of precision machining.

I avoid like the plague "rebuilt" equipment, unless it's done by a shop to factory new standards. That would include a detailed inspection report on the machine, squareness of column to table, flatness of table movement, full inspection report of the downfeed screw and so on and so on. The inspection itself would require an extensive assortment of expensive inspection equipment.

Then there's the spindle to deal with.

I'd expect a warranty approaching what the factory gives on new machines.

I don't want to discourage you, so I suggest you buy one and get started. If nothing else, it'll be a valuable learning experience.

DR, perhaps you feel like I do that there are a lot of people who do half-assed work and find any way they can cheat because they feel this is the only way they can make a profit.

I'm old enough and been through this kind of learning situation enough times to know just how badly I'm going to screw myself over and that paying Harig aprox $5,500 to do a rebuild would be much, much cheaper and probably much smarter. Apparently I'm not very smart and enjoy losing money and time this way.

In any case, thanks for the encouragement.

beckley23
04-11-2009, 09:58 PM
Most, if not all, of the tools needed are discussed in MTR. The one tool not discussed is the BIAX power scraper, you may or may not need it, but there is no way I would tackle a hardened surface without one.
Turcite, Multifil 426, etc., are way strip bearing materials. I am familiar with Multifil, which is a bronze impregnated Teflon, that has been etched on one side so that epoxy adhesive will adhere. It is very easy to scrape, in fact I won't use the BIAX on it, but will hand scrape it.
If possible, get in one those scraping classes that are arranged every now and then. Forrest Addy has, in the past, been the instructor. All the reports that I've read on PM and HSM say good things. Do a search on this BBS as well as PM, for scraping. There is a lot information that is helpful. I wish these boards were around 30+ years ago, it would have made my learning curve easier.
I admire your desire, you are in the same situation I was all those years ago. All I had was MTR, and the desire.
Harry