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Would you rather replace turcite or scrape plain bearings?

Agfrvf

Aluminum
Joined
Feb 5, 2018
I hate throwing out old machines and I have a knack for giving oldie but goodie machines new life. If you had to restore a 4020 size machine would you rather scrape plain bearings or replace turcite? From my understanding the turcite is a sacraficial element.
 
If you are talking about a 40 x 20 CNC milling machine, the whole machine is a sacrificial element. There are so many good quality older machines available for such low prices, there's no way it makes sense to rebuild a crappy one.
 
I hate throwing out old machines and I have a knack for giving oldie but goodie machines new life. If you had to restore a 4020 size machine would you rather scrape plain bearings or replace turcite? From my understanding the turcite is a sacraficial element.
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advantages of turcite is its replacable and the opposite metal side has much less wear so less machining or scraping needed on metal side often only .001" or .002" removed on metal to even out wear marks
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turcite epoxy bond can fail if lack of oil the turcite gets hot. so replacing turcite is actually a good thing. if you ever removed turcite you would easily notice difference in new turcite is extremely hard to remove and old turcite sometimes comes off all too easily
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turcite compresses slightly so it helps absorb vibration and less rattling vibration. this slight compression helps with slight unevenness. slip stick or pressure buildup then slide jumps is less, you get smoother motion with turcite usually
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by the way on gibs used to tighten slides some prefer spring loaded screws that always apply some pressure. you can get set screws with spring loaded tips of different compression force. hard to describe but purpose is so nothing is loose loose, always some pressure on it. similar to anti backlash lead screw nuts
 
Scrape plain bearings? What sort of machine are you talking about? CNC VMC like Wes is talking about? I disagree with him as I have helped several small companies re-turcite the old machines (I use Rulon 142 that is same product made by another mfg.) It is easy to replace and it scrapes like butter. If you want some help replacing it I'll volunteer to help for 1/2 price labor plus expenses in January - April as I am up in MN....lol You buy the material.

For him or any other where it is warm in the winter...lol
 
It might make sense to replace turcite and repair ways on a machine you already own and know has been taken care of. But, to buy a worn out commodity level machine tool with the intention of rebuilding it does not make any sense.
 
its like buying a 20 year old car. its usually got a lot of different problems and or worn out parts.
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often its the inability to get replacement parts especially electronics and old computers and sensors that determines whether to fix. like do you want to spend over $5000. and a lot of labor to get a old car working again only to have something else break on it a year later
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Jay Leno I believe had to buy a machine shop to make custom repair parts for his many cars. and many parts it can take considerable time figuring out how to make parts for it.
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take a simple shoulder eye bolt used for lifting motors and stuff. you can buy a drop forged one for a few dollars. if you try to machine from solid material it could easily cost over $200., the drop forge die equipment is expensive to make but once made the cost comes down by hugh amounts to make the eyebolts. some electronics you could easily spend $5000. or more to recreate a $5. part. often the problem is no drawings, that is do you have drawings on every part on a car ? sometimes hard to recreate a part just by looking at old worn or broken part
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i have seen a splined heat treated alloy steel shaft part you could easily spend over $2000. to recreate a broken part. actual cost can be 10 to 100x more than expected. some gears might be cheap when mass produced but when custom made the costs can skyrocket much much higher
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take for example a $20. dial indicator. ask your self if you made one how much would it cost ? $200 ? $2000. ? $20,000. ?
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or take a iphone. you couldnt make a cell phone for $10,000, some electronics no way can you custom recreate one or at least not easily
 
recreating repair parts some people who make the parts in the original factory couldnt make the parts with out detailed work instructions.
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literally figuring out how somebody did something long ago is not easy especially if clamping lugs used to hold parts originally were later machine or cut off.
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taking old machines apart i have seen where you had to follow 10 different steps to access screws to take apart and if you didnt have the work instructions without Xray vision it is basically impossible to take apart without breaking something. it can be extremely difficult fixing old machines and often it never gets repaired to anywhere near its original condition even years later
 
For clarity I am looking to buy one. I have some experience using them with an instructor over my shoulder. Currently I am manually machining my parts but I cant keep up with demand. Machining mostly 304 some 6061, need rigid tapping and the envelope for a run at a time. Been looking at ones in my area but they keep getting snapped up or are way above market. Travel time is hard for me at the moment so I may have to take a shot in the dark from a re seller.
 
The mechanical powerfeed on my VN2 is not in any drawings. Still took it apart looked for wear, cleaned and put it back together. Runs like a beast. My back ground is engineering and I still have most of my componet manuals. I can normally find an OTS part to modify and make work.
 








 
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