Scraping beaten up way end / how long should be the straightedge ?

Hello !

I have a big surface grinder (2500mm or 100 inches stroke), which sat unused for 10 years.

Y way end was exposed and of course some village idiot used way end as an anvil so it has some dents. Not very bad but they should be scrapen off. As I live in Estonia, we have no service like that available and I think I could manage it.

But first, as I have no trustworthy straightedge available, I think I will buy a granite straightedge. Can somebody suggest, how long straightedge is needed when the "damage" is about 200mm long ? Is there some rule of a thumb ? 2x or 3x or something similar ?

Afterwards I will post some pictures as this animal needs some more adjustments and repairs before it gets back to service.

Thanks !

If they are small dents at the end of the stroke and the machine grinds good. Depending on the depth of them, I might leave them alone. Or drill holes and fill with cast iron plugs. Scraping the bed and table of a 100" machine is a HUGE job just because of a few small dents.

The rule of thumb on a SE is you use one longer then the way or the longest one you can find. Most of the time on normal wear machines one scrapes the middle first as that is where they wear. Then lap in the ends. In your case you should scrape the dented end first until they are gone and then lap in the rest of the bed and then MATCH fit the table to the bed. I would also remove the table and grind under there to release the stress built up under the rusted magnet. Or power scrape it before match fitting the ways. Another thing you can use to keep the ways on the original alignment axis, is to use the clearnance surface that are next to the ways that were machined into the base when new. Many times it is a wall to keep the coolant and grit out.

Diclaimer: I have not used the following method but believe it may be applicable in this circumstance:

If the OP could beat the bushes to find a pair of LVDT levels (example: Millimar - Electronic levels - differential level system - Mahr Metrology) he might save his back and side-step the need for hoist equipment and a 10 foot SE and surface plate to check it. Using a maybe 3 to 6 foot SE and the levels or even older optical equipment, I believe a satisfactory job could be done. In his case I'd bet on finding levels or optical equipment before finding a huge SE and plate.

Denis

He could also just stone off the part of the dent that is proud of the surface and call it a day. No reason to buy thousands of dollars of equipment.

A precision .0005" or better machinist level can be used along with the bigger SE. I forgot to say that this AM. When people start talking about lasers and electronic levels I all ways say, "how did we do it before they were invented"? At Defense Logistics East (army/navy machine depot) that had a new Hamar wireless 3 axis laser and it worked super and was fast, as it put the results on a laptop and chart program, but the paid $30,000.00 for it. As Sip said a bit on the expensive side unless your a zillionaire or they are spending our tax dollars.

Maybe, by beating the bushes a bit, the OP could borrow some equipment or perhaps buy an older generation level for $1200 like this one: Mahr Federal Millimar Precision Electronic Level | eBay

After he is finished, he could sell it for a little more or less than what he paid for it. I've done that with other equipment enough times to realize I am only temporarily parking some money in the item while I need to use it. Just depends on how resourceful he is and what connections he has. Optical levels are also available for less than the electronic ones of course.

So, many ways to skin the cat. I think he came here asking for suggestions. It is up to him to determine what might work for him given his financial (unknown to us) and equipment availability (unknown to us) circumstances.

I hope he provides some follow up on what he does and what he learns about the condition of the ways beyond the simple dings. That grinder's ways may be straight as the day it was made (wishful thinking) or may need a lot more than the obvious dings stoned off. Having adequate equipment to assess its condition seems like a pretty basic need and what he is asking about.

Denis

SIP6A said:

He could also just stone off the part of the dent that is proud of the surface and call it a day. No reason to buy thousands of dollars of equipment.

Click to expand...

This.

"First", anyway.

At this point, not yet certain it even has a still-usable SPINDLE.

Another vote for SIP6A's solution of getting a good stone and a pint of paraffin ( kerosene I think in the US ).

Regards Tyrone.

Tyrone Shoelaces said:

Another vote for SIP6A's solution of getting a good stone and a pint of paraffin ( kerosene I think in the US ).

Regards Tyrone.

Click to expand...

Another vote for SIP6A, I would stone off any high spots put it to use and decide later what to do if it is out of spec.

dee
;-D

I vote in favor stoning the the dents too.
The very next step should be testing the wear in the table by placing a parall on it (it doesn't matter if it rests on the table directly or on the chuck, as long as it rests on three points). Put an indicator in the head and record any vertical deviation from linearity: that will be the reciprocal of the curvature left on any piece you grind: you will need to answer the question if you can live with if, or you need to fix it.

Paolo

Thanks for very good suggestions !

I think that stoning would be enough.

My goal is to restore that machine more for stock preparation and occasional punch/shear/bending blade sharpening, all of them do not require high absolute accuracy.

Spindle bearings have been changed and should be good. Grinding wheel is huge and I hope that stock removal is impressive.
Cutting fluid system is awful and full of petrified stone-jelly mixture.

I will post some pictures soon. Oiling grooves look very strange so I need some suggestions about remaking,

Madis Reivik said:

Cutting fluid system is awful and full of petrified stone-jelly mixture.

Click to expand...

Acquired meself a largish DP and a medium mill like that. Sore tempting to just pour concrete into the base coolant tanks and fab an external!

..but... I had some gadgetry lying idle so..

Kitchenwares. Cheap soup spoon or ladle. Dig out what is easy to reach, and then..

Find yerself a throw-away priced (probably mostly plastic, might be 12V DC) centrifugal pump, basic filter. Mix-up some washing soda or Purple-power, put a timer to circulating the suds for a few minutes several times an hour, not 24 X 7.

Go do other things for about a whole WEEK. Or TWO weeks.

Still messy to dispose of, but waaay less hand-labour will be required.

2CW

I was cleaning out the filter tank on a large cylindrical grinder one day. One of the office big wigs saw me with a wheel barrow full of the heavy blue/grey sludge that came out of the tank.
He said. " I'm relaying my garden path Tyrone, if I get you some old oil drums will you fill them up with that material. I really like the colour. I'll mix it with cement for grouting in my crazy paving ".

So I did this for him. He went away with the sludge happy as Larry. He was really pleased with the grey grout matching his grey slate garden path.

Until the next time it rained ! The nice blue/grey colour turned to a shitty brown as the steel grains in the sludge turned to rust !

Regards Tyrone.