Surface Grinder refurb

[Pete RimmerParticipant @peterimmer30576]

No roller ways on an Eagle, they are definitely entry-level. my old J&S 540 had plain ways too.

[Tony RayParticipant @tonyray65007]

Hi Steve,

How's it going? – haven't seen anything from you for quite a few days.

[Steve355Participant @steve355]

Posted by Tony Ray on 27/10/2022 12:45:26:

Hi Steve,

How's it going? – haven't seen anything from you for quite a few days.

Hi Tony, thanks for asking My wife doesn’t care about my project.

l’ve been going a bit slower for the last week due to half term and work etc. But I have been making some progress with the knee nearly done. I have a fairly clear weekend so I’m hoping to get some hours in… this scraping is a really time consuming business. But hopefully I’ll get the column and knee back on the machine this weekend.

One thing that did turn up in the post is a level that I got on eBay. This seems to be a very well made and useful tool, given its very smooth and stable adjustment mechanism. At least, it has helped me double check my measurements. It has 1 in 10,000 divisions, so at 8 inches long, 1 division is 0.0008”. So indeed my table is flat to < 0.0005, probably 0.0002 in most places. Not perfect for a surface grinder but way better than the 0.004 I started with and probably good enough for anything I will do with the machine.

BTW I have switched over to the carbide scraper, with a little skinny blade I made to get into dovetails. I’ve been sharpening it with a diamond hone. I think the diamond disc I was sharpening with before was no good and the diamond coating had come off. I really could do with a diamond wheel of some sort.

No sign of the straight edge yet

More later this weekend, I have some dovetail measurement questions that I know will come up.

Steve

[Tony RayParticipant @tonyray65007]

I understand. I’m decorating at the moment; I do that when the light is good and disappear down the workshop when it’s poor.

Your table flatness is fine, once you have your magnet in place and ground in that will be your working surface. To sharpen your carbide I recommend something like these

1 Set 6 Inch 240/600/3000 Diamond Coated Wheel Lapping Disc Flat Lap Wheel Kits

4” ones are also available, you just need a backing plate and some means of rotating them. Stefan G made avery nice 24V powered slow speed grinder attaching them to the backing plate with magnets and two drive pins. I copied it and it works beautifully, I also use it to touch up carbide inserts and HSS lathe tools. My grinding rest is a 3D printed tower with 5 degree iirc top surface.

Thats a very nice level.

[Mark Davison 1Participant @markdavison1]

Tony, what sort of motor did you use for the slow grinder/lap?

[Dave SParticipant @daves59043]

I just used a normal single phase motor and a steel disk. I load it with 7 micron paste to polish:

You can see the motor in the background

Dave

Edited By Dave S on 29/10/2022 20:42:13

[Tony RayParticipant @tonyray65007]

Hi Mark,

I adapted one of these.**LINK**

but I paid £30 for it. I copied Lookcreations on the tube. The worm drive that provides the speed reduction to the whetstone is really poor so I would not go down this route again. Instead I would copy Stefan Gotteswinter and us a 24v dc geared motor, there is lots of choice on eBay. DC motor speed controllers are also readily available if needed.

[Steve355Participant @steve355]

The good news….

Of the bearing surfaces I’ve now scraped the column, the table (top and ways) and the knee (horizontal and vertical surfaces). All seems to be reasonably flat and square: I’m now starting on the carriage between the knee and the table.

The not so good news….

Measuring parallelism of the column dovetails, it looks like about 0.009 of wear.

Column dovetail

I reckon I need the straight edge for this, which hasn’t turned up yet, despite chasing. Even then it’s a significant job.

[Mark Davison 1Participant @markdavison1]

If you have bought an HR Lamb straight edge from Clive be prepared to be patient ! It will be worth the wait when it arrives.

[Steve355Participant @steve355]

Posted by Mark Davison 1 on 30/10/2022 13:05:58:

If you have bought an HR Lamb straight edge from Clive be prepared to be patient ! It will be worth the wait when it arrives.

I kind of expected it, he’s clearly very busy, and he obviously doesn’t make any profit out of straight edges.

Even when it turns up, obviously I have to scrape it flat! Although I expect it will be pretty close to flat when it arrives.

I’m kind of thinking that once I finish these last few small surfaces, if I don’t have a straight edge, I’ll put it back together and treat the dovetails as a second project.

[Tony RayParticipant @tonyray65007]

That’s not a bad idea, you may be pleasantly surprised how good it is without that last bit of work.

[Steve355Participant @steve355]

Posted by Tony Ray on 30/10/2022 16:06:48:

That’s not a bad idea, you may be pleasantly surprised how good it is without that last bit of work.

I can’t help thinking though that with such a big dip that the table will “flop” in that area. It’s easy to see why it happens, there’s a lot of weight pulling against the dovetail around there, if it’s scraped it will surely hold oil much better.

Taking 9 thou off is a lot – and the wear area is quite small, maybe 1/4 of the length of the dovetail. That’s a lot of scraping.I’ll have a look and see if the bulk can be removed with a file.

[Steve355Participant @steve355]

Update…. I have finished the scraping of the main services to a reasonable level, obviously some could be better, but I could probably keep at it for weeks. The problem is still the dovetails. Despite assurances, I still haven’t got the straight edge. so I have started putting it back together to see how it works, despite the 0.008 wear on the vertical dovetails.

I have been pleasantly surprised by the squareness of the knee with the column, it’s pretty much bang on. However, predictably, adjusting the gibs on the knee doesn’t really work very well due to the wear. If I tighten up the gibs while the knee is in the wear area, when I lower the knee, it gets stiff and interferes with the gear that is raising and lowering the knee, potentially causing it to come loose.

given that I know this, I can work around it, in practice for any particular job the amount of vertical movement I need is very small. But at some point those dovetails need to be sorted out. I am tempted to carry on and put the machine back together this weekend carefully, measuring and checking everything as I go.

[Steve355Participant @steve355]

Stupid question no doubt, but what are these oil reservoirs called/how do they work? Do I need a wick of some sort?

Steve

 

Edited By Steve355 on 12/11/2022 10:33:01

[Pete RimmerParticipant @peterimmer30576]

Those reservoirs should have a losenge-shaped felt pad in them. They are just a giant oil wick that lubricates the table as it slides over.

[Tony RayParticipant @tonyray65007]

The absence of your straight edge is bothersome.. What length did you say the column dovetail is? At least you’ll be working on a narrower surface so metal removal will go faster. I think the knee ways are poorly designed, that’s why they have worn excessively. I would suggest putting in some oil grooves on the moving knee surface ( less work than doing the column like diagonal zig zags. Those grooves should stop before the ends and I would install way wipers at least on the top side; you can make them out of the felt you’ll need for the lozenges.

[Steve355Participant @steve355]

Posted by Tony Ray on 13/11/2022 08:11:34:

The absence of your straight edge is bothersome.. What length did you say the column dovetail is? At least you’ll be working on a narrower surface so metal removal will go faster. I think the knee ways are poorly designed, that’s why they have worn excessively. I would suggest putting in some oil grooves on the moving knee surface ( less work than doing the column like diagonal zig zags. Those grooves should stop before the ends and I would install way wipers at least on the top side; you can make them out of the felt you’ll need for the lozenges.

Hi Tony. Well, I put it all back together yesterday for tests today. It is most annoying but to be honest I could do with a break from it. I have plenty of other projects to get on with, and I really want to get it to something usable.

It has the oil grooves you mention on the gibs and opposite dovetail of the table. So I can see what you mean.

One question, I’m guessing I need a special oil gun to fill the reservoirs from the oil nipples. Any idea what type? I’ve never come across this before in my very limited experience,

Steve

[Pete RimmerParticipant @peterimmer30576]

I had to make my oil gun from an old grease gun. I cut it in half, turned a heavy cap to serve as a base and welded it on. Cut the handle down to 6" long and filled it with way oil.

[Tony RayParticipant @tonyray65007]

I understand the need for a break and you can tweak the gibs to suit whatever part of the height range you are using.

Oiling these old machines, in fact any machine seems to me much harder than it needs to be. I have machines that have nipples that it looks like they are made for grease gun attachment ( but require oil), some that look like a nipple some that are the flat ball oilers. I dislike all of them I have recently put a piece or 6mm id PVC tubing on the end of an oil can; that has helped greatly with the second type and I expect it to work on the grease nipples type as well.

If you have room I would look at fitting lidded oil cups where you can, that's a job that I need to get around to myself.

[Steve355Participant @steve355]

Update….

It’s all back together now and I’m running some tests. I didn’t scrape the dovetails as my SE (still) hasn’t turned up. It worked almost very well, see pic. It’s flat and thicknessed to +/- a few tenths, except at one end. At that end (right in the pic) the surface finish changes slightly and the thickness is about 0.004” less. I’d bet that that occurs when it crosses the centre of gravity of the table.

Problem 2 is the table gibs. If I tighten them enough to ensure there is absolutely no lateral movement of the table, then if I wind the table to either end of its travel, it gets very stiff. I’ve messed with it for ages trying to find a sweet spot, but to no avail. I have a nasty feeling that it is caused by dovetail wear.

Any thoughts welcome.

Steve

[peak4Participant @peak4]

I'd guess at dovetail wear going by the way mine behaved.
My Centec is similar, particularly as I have a large(ish) single phase motor at one end of the table to provide the power feed. At far right extension, the table certainly leans a little.
In practice, I keep a universal dividing head bolted down at the other end to help balance it up.

Bill

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