Member postings for Steve355

Right, back from trip #1, off on trip #2 for 2 more weeks, so I’m thinking about my surface grinder project for when I get back from that.

while I’ve been away, a couple of things came in the post… I have a carbide scraper, which removes way more material than my vintage hardened scraper. And a 1/10,000” clock, which didn’t work of course but I seem to have fixed it. I’m now pretty convinced that my surface plate is within a few 10ths.

The question is, what should I get for the project? It a choice between:

1) bigger, new surface plate. The one I have is 18x12 and seems ok but it could be flatter. 800x600mm is the absolute max, and I don’t really know where I’d keep it.

2) camelback straight edge - but it would need scraping, so I’d have to rely on my existing surface plate for that.

The longest ways on the grinder are 34”. Then straight edges are either 24 or 36 inch. If I could I’d go for the smallest one that would work.

I am ok to invest in some kit as I have 2 mills and a lathe that would benefit in the longer term.

Any thoughts from an experienced person?

thanks

Steve

Traditional roofing is really interesting, I’ve built a couple of small roofs, slated them, done the lead work, ridge tiling etc. don’t knock it until you’ve tried it. Getting it all straight isn’t easy. Knowing your birdsmouths from your barge boards is useful too when the cowboy builders come around. Besides, making a roofing square would be a nice milling project.

thats a kind offer Pete and I may take you up on it. I’m actually off to the US tomorrow for 2 weeks then another 2 weeks on holiday. So my project is about to be delayed for a month, sadly. But once I’m back, I’ll be raring to get on with it.

I may try to pick up a comparator when in the US, I have an idea for a simplified repeat-o-meter thing.

I’ve had another go at this this morning, and got altogether better readings on my surface plate

DTI on surface plate

Displacement in most places is 0-0.0002 with a few spots that are maybe 0.0005. But it is difficult to do well, and the surface gauge spring is very springy (is this normal? I doubt it) and difficult to adjust accurately. If it slips off the gauge block, it often needs readjusting back to 0. I need a better surface gauge.

The errors are as likely to be me/the setup as the surface plate, I’d say.

The question is, is this surface plate good enough to work with the surface grinder table/ways etc? I wish it was, but probably not. But it isn’t as far out as I feared.

Here’s the thing… last weekend I lashed up a little metalworking bench. The idea being to get all the metalworking equipment out of the woodworking side of my shed, due to grinding dust, oil and grime not mixing at all with woodworking. Had I realised that I was going to want to find a space for a bigger surface plate, I could have done it differently. Here’s a vid of the area, the surface grinder has now moved to a more sensible position. See surface plate in its spot behind the DW.

Metalwork side

Edited By Steve355 on 07/08/2022 08:14:10

Imdeed, I should have thought of this. This setup is functioning exactly like winding sticks in woodwork. It is amplifying any difference between the near and far sides of the base (and then adding on any difference at the location of the probe). In my defence I was just copying 2 experts from YouTube!

I’ll think about how to do this better, the repeat-o-meter looks great, with the snag that the base needs to be surface ground (bit of a problem at the moment!)

For me the large surface plate is a real problem. I just don’t have room for it, my shed floor space is full. I’ve just moved out the kids bikes to accommodate the surface grinder. I could possibly find a space to keep one on a shelf under a bench but they aren’t easy to whip out when needed. That’s why I got the 18x12 plate - I have a specific space for it.

I actually have an old scriber stand, earlier I spent some time trying to map my surface plate to see how bad it really is. But it’s all so bouncy and unreliable that after an hour at it I am none the wiser. Each time I return to a square I get a different reading. Of course this could be because the base is not in exactly the same place, but even if it is I often get a different reading.

I do wonder if I should buy another 18x12 reliable surface plate, or even a smaller one and use it as a reference to scrape my existing surface plate,

Hi Tony

Yes, I’ve seen that channel and it’s very informative. Watching that yesterday inspired me to order a 0.0001 plunger dial indicator and proper scraper.

I watched another vid by suburban tool inc about measuring surface plates, and checked mine out this morning, and it’s out by at least 0.001 in places, possibly more. It was a £40 eBay knock off so I’m not surprised, probably fine for what I’ve been using it for - various bits of measuring and scribing, but not suitable for blueing.

I will probably end up getting a new surface plate as you suggest, but it’d have to be pretty big, and I don’t know where I would store it or how I’d handle it on my own. A lump of granite 32” long or so must weigh a ton, or something approaching that. And I have a touch of arthritis. Or could I get an 18x12 one for my 36 inch ways?

I do wonder whether I could re-scrape my existing plate. And how big a flat surface I’d need to get it flat.

But what I do need is at least one thing in my workshop that is definitely, reliably flat.

I had another look at Bill’s Flickr pics last night. Bill - if you are reading, what did you use, particularly for the large surface on the Z axis of your grinder? I saw a weird straight edge being used for the dovetails, and a forest of DTIs, but I couldn’t work out how you tested for flatness when the column was strapped to that gurney in your kitchen (respect for that! I wouldn’t dare)

Steve

Sounds good. A bit like a French polishing mop. I tried it with a rag and it didn’t work too well. I will make a dolly then and see how it goes.

thanks for the tip

>>if you can find a reference to scrape them from.

That be the problem! Even my surface plate is only fairly flat. I think I need something that is reliably definitely flat so I can use it to make other things flat.

Brilliant. So I wasn’t getting the same results from my surface plate/DTI measurement as with the micrometer. Turns out that the top of the table, somehow, isn’t flat. I’ve checked the surface plate and it seems ok.

The micrometer reads 1.999” at A and B. The DTI differs by 0.005.

I think it was Bill earlier who said he started by scraping the top of the table, and then use that as a reference surface. I did check the top of the table with feeler gauges, and it seemed to be fine down to one thou. But clearly it isn’t. Or something isn’t.

Edited By Steve355 on 05/08/2022 10:11:41

I’ve measured the thickness of the table and it seems to mostly now be between 1.899 and 1.901. It was difficult to measure the extremities - had to use a depth micrometer, I don’t think the most outboard measurements are particularly reliable.

So 1.899 to 1.901 - I would guess that’s a reasonable tolerance to start the bluing/scraping process?

I had a go at bluing using the surface table, but 1) I don’t have a roller, one is on order but hasn’t turned up yet. And 2) it gets wobbly and unreliable at the extremities, it’s an 18” surface plate and a 32” grinder table. So I can see the benefits of the straight edge.

The thing I am not understanding about the straight edge is how to keep the ways parallel to the table, and free of twist.

I’d take up Pete’s kind offer, but if I could find one suitable I’d probably buy it. With all the machine refurbing I’ve done so far I have stripped, cleaned, replaced bearings etc but as for the basic workings of the machine I’ve had no ability to do anything for accuracy other than adjust/shim etc. I have several machines I can go back over if I have an accurate surface grinder and scraping skills/equipment and get them to a much better condition.

Pete, that’s really interesting, thanks for the tips. Using a file to get down to a flatness that is practical for scraping will surely save a lot of time and effort, I have a 2” micrometer, but it’s not a vernier one, but nevertheless is probably ok?

what’s the next step? Do you blue up the straight edge and use that to “print” the surface for scraping?

not too close to Kent, I’m in Herts

Steve

Hi Bill

I did see that, and I’m considering getting one of that guy’s scrapers. But I’m off to the US on Monday, I wonder if in can find something cheap and good over there.

The tight spots are simply spots at edges or corners where there is a high spot surrounded by low spots, so not even real tight spots yet!

Because the ways are long and thin, it’s difficult to do a nice pattern. Much easier to scrape along the ways. It that way leaves behind high spots.

if it’s 2 tenths then that’s 5 passes for 1 thou. I reckon I’m doing about half that,

measuring is really difficult. I have managed to attach the DTI firmly to a height gauge at last, but it easily gets out of kilter If the probe gets knocked. I could have a go with a plunger type dial indicator, but it’s less accurate.

my surface plate is too small, but there’s not much I can do about that,

All good learning experience!

This scraping business is not as much fun as I had imagined!

It’s very slow going
it is hard work
it’s easy to go too far

its difficult to get into tight spots

I watched a video on YouTube where the chap measured the depth of the scrape at up to 0.0005. If only,

I can see why this old Tony started by milling his, I have to take off up to 0,005 in some places. Perhaps it’s time for that long carbide scraper, if I can find one.

I basically saw some scraping coming on one project or another, so I got a few old scrapers from eBay, and practiced on some mild steel. It worked ok, was interesting to watch the blue spots spreading as the piece flattened. But that’s all I did really, and yes I was regularly honing the edge. You are correct that the larger scraper it for curved surfaces but I can grind it square.

I think I may have a flat bar DTI holder somewhere that would allow me to attach it to the height gauge.

Perhaps tomorrow I can start!

Thanks Bill, seems like the place to start is the table then. On the surface plate I can’t get a 0.0015 feeler gauge under it anywhere, so I guess I can assume it can be used as a reference surface, I don’t want to resurface that unless I have to,

I’ve started to take readings along the bearing surfaces and the worst it gets is about 0.004 with the expected dip in the middle. One problem I have is that I don’t really have a proper stand for the DTI. I’m using a height gauge attached magnetically, but I’m not confident that if I move it to measure the other side, it won’t wobble. I can’t seem to find a suitable stand on RDG/Chronos.

I have a few old eclipse scrapers I bought from eBay. I doubt they are carbide, but I expect they were perfectly usable once upon a time, one has a rounded end but I could easily grind it more flat. Do I really need to invest in a carbide scraper? Are they that much better ?

Hi Bill, thanks for your post - very inspirational. Your Flickr album too was really interesting, all the setups you devised to measure the different dimensions and angles too.

As for my equipment, I basically have a 12x18” cast iron surface plate and a bunch of DTIs, mics etc.I have a Dore Westbury mk 1 and a Burke #4 horizontal, both of which work ok but part of the point of getting a surface grinder was that I would be able to sort them out properly.

My question is, having done this, where would you start? I don’t want to do any work that isn’t required, but I do want to do the work that is required, if you see what I mean. I’m thinking I strip back to the Z axis, indicate that and see how it is. If it’s fine, all well and good, if not, then that’s where I need to start.

Steve

Pete - yes that’s exactly what I’d surmised. And that’s why I need to take a step back and start from the beginning, measuring the Z axis to make sure it is working acceptably, there is a lot of evidence of scraping on the Z axis ways, so I’m hoping that at least that part is in reasonable nick.

Steve