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Portable milling/grinding machine for machine way reconditioning

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PekkaNF:
Hello,

I have pretty old mill and it's ways need reconditioning. I have come to conclusion that outsourcing the work is not possible. Way too expensive and involved to work companies that really don't want to cater hobbyist. Ways need to be milled/ground to acceptable accuracy, now they have serious wear and that produces almost 0,4 mm dip in the 500 milled distance....I would be happy with 0,02 - 0,04 mm planar inaccuracy on 500 mm distance. Nothing impossible.

Ofcourse I could scrap it and start looking for a little less used, but here mills that are way better are really big industrial ones. Small hobby size (like bridgeport or such) are not often available and they are really expensive when they are.

So before scrapping my scrappy mill I might as well try fixing it and if I break it, I least learn something. Amount of metal removal necessary excludes manual scraping. I need to use power tools.

I have seen magnetic drills and mills bit like this on sites I used to go to:
http://www.hydratight.com/sites/default/files/products/images/geniSYS_II_milling_machine_product1.jpg

I never seen an linear portable mill, but apparently there are some:
http://www.hydratight.com/sites/default/files/products/images/geniSYS_II_milling_machine_product1.jpg

http://cdn.powermag.com/wp-content/uploads/2012/11/520004de14df6-Linear_Mill_-_Gantry_Mill.jpeg

Now the interesting design question: How to build "frame" which is a) bolted to milling machine frame to mill/grind milling machine upright flat ways straight, b) to mount that will hold table and it has dovetail ways, c) possibly knee.

Knee I might be able to farm out for milling least, maybe even grinding, but table is way too big.

I have been checking as much as I can without dismantling the milling machine (I need that on this condition to make some parts) and interestingly looks like there are part of the ways that still has original scraping left, I could use them as a reference to record shape of the ways and keep book how much screws and mounts have to moved to fit all parts together.

I considered plasma cut steel parts and welding....fast and easy, but I don't have immediate ways of heat treating them. I know that those structures have no long term stability, but for one-off work how much they live in a day/two time span? Or do they spring which ever way and live all the time during the stress of milling/grinding (not the rig/frame) but part?

I'm not considering concrete in any form. Makes a real mess on reuse of the metals and it shrinks first 400 years, first very much.

Most I'm considering hot rolled steel, minimal machining and all bolted joints.

I may be able to persuade one machine designer to give go/no-go advice on dimensions and such. Plan is to use some parts I have all ready and build bare minimum of structure/tools I will not have much use after.

Pekka

awemawson:
What is the mill Pekka? A knee mill of some variety by your description, but a photo and rough dimensions would help us cogitate your problem a little better.

PekkaNF:
Damn. I should take pictures...it is small knee mill, about 1,5 metric tons in weight. Originally horizontal mill, but it has a universal vertical head - no drilling pinion. Maybe 3kW motor, gearbox 8-speeds from 25 to 700 rpm or so...and clutch.

Table is about 1000*250 mm and all parts are heavy :lol: Table and it's mating part are the only dovetail guide, others are flat guides, some 100 mm wide. Table/knee and horizontal flat guide have most wear.

For a German engineering lubrication is funny and and it has seen use, first school, then truck "shed" where they probably forgot to lubricate it.

Coolant tank was shot when I got and cardan shaft for feeds too, but gear and coupling works well. I will not win prizes but will shift some metal even when it is worn out. Someone had spooked the sound of the flat belts (squeeelll- clonk-clonk-clonk) and I got the cheap...delivered. I bought a new endless belt and it behaved well.

I have been looking a small mill/drill of about 300-1000 kg range, but good ones are completely out of my reach and cheap ones are crappier than mine.

Pekka

PekkaNF:
Compulsory pictures.

Biggest and most annoying wear is on X-axle, table/knee axis. Y-axis looks weird, but has little impact. Z-axis has a dip in most used place on back of it, where the knee is hanging.

Pekka

RotarySMP:
Do you have a surface plate and straight edges long enough to quantify the wear? It is extremely unlikely that you can fabricate a temporary mill or grinder able to improve this machine. You are better off downloading the PDF of Connelly's Machine tool reconditioning posted here yesterday, hacking a cheap sabre saw into a DIY Biax, getting access to a surface plate , scraping it back in.
Mark

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