Surface Plate & Height Gauge recommendations

[duncan webster 1Participant @duncanwebster1]

Posted by Lee Jones 6 on 01/06/2020 16:00:07:

Posted by larry phelan 1 on 01/06/2020 15:56:48:

I spend my money on good Irish Whiskey, can,t do much better than that !

Now I know you're fibbing.

*Good* Irish Whiskey indeed. ​​​​​​

Whatever next? Quality import tooling?

how about Welsh Whisky **LINK**

or even English **LINK**

There are quite a few English whisky makers, unfortunatley all rather expensive, so I'll stick to Scotch, preferably Islay

[Robert Atkinson 2Participant @robertatkinson2]

Posted by Barrie Lever on 02/06/2020 12:39:26:

Dave

I keep looking for a CMM but no luck yet, will update if I am successful.

B.

Work threw one in the skip last year – literally The Rennishaw touch probe was still attached but smashed up aginst the edge of the skip.

[Ron LadenParticipant @ronladen17547]

I splashed out on a granite worktop protector from Dunelm, 400 x 300 x 15mm cost £10 and for a tenner it is easily good enough for what I will be using it for, some occasional marking out and measuring and parts assembly that need a flat surface.

I havnt got a height gauge at the moment, currently looking for one and will probably go with a digital but I would be ok with a vernier type. Not having a height gauge yet I used the Mitutoyo Digimatic as accurately as I could to check out the plate. I placed a bar of silver steel across a pair of V blocks and measured the height at each end, I then moved the blocks and bar around to numerous positions on the plate checking against the original measurement. I was pleasantly surprised at how good it was, 80% of the plate was within 0.001" a couple of places towards the edges and corners 0.002" and one corner was 0.003".

I dont know if I have been lucky with a good one or if they are all fairly close.

[Anonymous]

Unless I've misunderstood what was measured I don't see that it tells you anything about how flat the plate is? If you put the rod and V-blocks on a large sphere and move it around the ends of the rod will stay at the same height relative to the surface.

Andrew

[Ron LadenParticipant @ronladen17547]

Thats not how I saw it Andrew, if I move the two blocks to a different position and one of the blocks climbs or lowers surely that would raise or lower the bar at the opposite end wouldnt it..?

[Former MemberParticipant @formermember32069]

[This posting has been removed]

[SillyOldDufferModerator @sillyoldduffer]

Posted by Ron Laden on 04/06/2020 15:11:44:

…

I dont know if I have been lucky with a good one or if they are all fairly close…

They're made on a surface grinder and as these out-perform milling machines by a considerable margin, there's a good chance ordinary products will be impressively flat. Grinding wheels are composed of millions of tiny cutting points, often artificial diamonds, embedded in a matrix. As grinding wheels can be dressed very accurately, and wear corrected with optical guidance, a typical modern CNC grinder can work down to about 0.5μm. A precision grinder does considerably better, achieving accuracy expressed in nanometres.

Although CNC surface grinders are widely used to make granite worktops I doubt operators pay enormous attention to getting best possible results out of their machines, and some might be using older/cheaper kit that doesn't correct automatically for wear. Nonetheless, output is going to be fairly good because the product has to have a high polish for cosmetic reasons.

It's another gamble. Potentially good, but no guarantee. Worktops and tiles haven't gone through the next stage of surface table production, which is accurately assessing and correcting flatness to a specification. Nor are they concerned with temperature stability or rigidity. Plate glass is in the same boat; it's made by floating hot liquid glass across a bed of molten Tin. As liuid Tin is naturally flat there's a good chance the resulting glass plate will be excellent. Unfortunately, as the production process isn't deliberately going for flatness, random glass as used in a workshop might not be the best. Most of the glass in my double glazing is optically impressive but I can find a few panes with small imperfections if I look hard enough.

I reckon Granite and Plate Glass are both fully capable of meeting my flatness needs, but I'm very much in the 'good enough' camp, with no need – so far – for accuracy better than ±0.01mm.

Grinding in industry is extremely common. I guess more metal is cut with grinders than any other sort of tool. Pity we don't have high-end grinders in our home workshops because the results are fast and accurate with excellent finish. Unfortunately the machines are big, expensive, take a lot of setting up and several might be needed in a line. Brilliant for mass-production, rarely sensible for us ordinary Joes.

Dave

[Ron LadenParticipant @ronladen17547]

Thanks Barrie for the video I will give that a try, I do have a test indicator not a tenths one but it is 0.01mm and I have some slip gauges so it should give some idea.

I had the bar over hang at around 20mm but the test indicator is a better way of measuring than the caliper I was using.

Thanks again

Ron

[Former MemberParticipant @formermember32069]

[This posting has been removed]

[Anonymous]

Posted by Ron Laden on 04/06/2020 15:59:29:

………..if I move the two blocks to a different position and one of the blocks climbs or lowers surely that would raise or lower the bar at the opposite end wouldnt it..?

Yes it would, if the two planes on which the V-blocks sit are parallel. One issue is that the movement of the end of the rod compared to the movement of the V-block is reduced by roughly the ratio of the length of the V-block compared to the rod. Which is rather unhelpful.

If the two planes on which the V-blocks sit are not parallel (quite likely if the plate isn't flat) then all bets are off, as the movement of one end of the rod will be influenced not only by the vertical movement of the V-block at the other end but also by it's tilt. Without other measurements it would be difficult to determine which effect was the cause of any movement of the rod end.

No idea where SoD got the statistic that grinding moves more metal in industry than anything else. Most of the machine shops I've used professionally over the years didn't have any grinding machines. Grinding is good for precision and high quality surface finishes, but it's a relatively slow process. As such it's to be avoided unless absolutely necessary. One of the factors driving the development of inserts that will turn or mill hardened steel was to avoid having to use grinders for finishing operations.

Andrew

[peak4Participant @peak4]

Posted by Barrie Lever on 04/06/2020 16:50:18:

Ron………………….
Take a look at this video, I think you will like it, not a perfect approach but a practical solution, Don Baileys videos are really great IMO
**LINK**
Have you got an indicator like is being used in the video?
Regards
Barrie
Edited By Barrie Lever on 04/06/2020 16:51:35

I saw that video a while ago and used the same method to check out my piece of black granite worktop, hoping I could use it for scraping in some parts of a surface grinder.
Unfortunately it has dips of about 5 and 10 thou as well as ripples, and drops off at some sides, though it looks OK at first glance.

I did try a sheet of 6mm float glass on top to even out the dips, but found that heavy objects just bent the glass.
Next try was to make layered shims out of baco foil, but that didn't really work either.
I've now kept that for use as a clean surface on the bench and picked up a used 24" square cast iron plate locally.
This has a minor bit of rust staining, but for the most part, the original scraping marks are present.

Had I not found an affordable plate locally, the next plan was to use a different piece of unpolished quarztite worktop, and add some plaster to the top surface of it; whilst still wet, top it off with the piece of float glass, which would then be substantially supported and pretty flat. The trouble was, that I think the piece of new glass was actually warped by several thou because of the way it had been stored at the window shop prior to delivery.

The first job for the proper cast iron one was to scrape in the top surface of the main table, so I can use that as a portable surface plate to scrape in the main column.

Never really tried scraping before, and I'm very slow and not exactly good at it, but getting there eventually.

Stuart's Blue is the new woad for 2020.

Bill

[Ron LadenParticipant @ronladen17547]

Posted by Andrew Johnston on 04/06/2020 22:01:19:

Posted by Ron Laden on 04/06/2020 15:59:29:

………..if I move the two blocks to a different position and one of the blocks climbs or lowers surely that would raise or lower the bar at the opposite end wouldnt it..?

Yes it would, if the two planes on which the V-blocks sit are parallel. One issue is that the movement of the end of the rod compared to the movement of the V-block is reduced by roughly the ratio of the length of the V-block compared to the rod. Which is rather unhelpful.

If the two planes on which the V-blocks sit are not parallel (quite likely if the plate isn't flat) then all bets are off, as the movement of one end of the rod will be influenced not only by the vertical movement of the V-block at the other end but also by it's tilt. Without other measurements it would be difficult to determine which effect was the cause of any movement of the rod end.

No idea where SoD got the statistic that grinding moves more metal in industry than anything else. Most of the machine shops I've used professionally over the years didn't have any grinding machines. Grinding is good for precision and high quality surface finishes, but it's a relatively slow process. As such it's to be avoided unless absolutely necessary. One of the factors driving the development of inserts that will turn or mill hardened steel was to avoid having to use grinders for finishing operations.

Andrew

Point taken Andrew I should have thought about it a bit more.

Ron

[Anonymous]

Well that's odd; before I started breakfast I'm sure there was a post in this thread by JasonB explaining to Barrie and I that we knoweth not what we talk about with regard to SoD and grinders. But it now seems to have disappeared? May be SoD has more influence than we realise, and we should be careful in case the boys call round for a 'chat'.

Andrew

[JasonBModerator @jasonb]

There was, I did not read the last bit of Dave's post, the rest was about grinding granite which my reply related to so deleted it after re-reading Dave's post.

[Ron LadenParticipant @ronladen17547]

So out of interest I mounted the test indicator on a Stevenson block for stability and took a number of readings around the plate. Wont bore you with the details but basically the plate has a central area approx 10 x 8 inches which is good to 0.025 mm. You can see in the pic the indicator reading with the indicator towards the left of the plate having set zero 10 inches away on the right of the plate. From this central area the plate falls away towards the corners 0.5 mm at two corners with 0.7 and 1.0 at the other two.

I also did a basic test with a 4 inch gauge block and a strong torch looking for any obvious hollows, high spots ripples etc but didnt find any.

So as a surface plate it is not good but as a general purpose plate which has a decent centre section which will cover what I will be using it for its good, very good if you consider it cost £10 from a kitchen shop.

 

Edited By Ron Laden on 05/06/2020 09:03:59

[Former MemberParticipant @formermember32069]

[This posting has been removed]

[Former MemberParticipant @formermember32069]

[This posting has been removed]

[Anonymous]

Posted by JasonB on 05/06/2020 08:32:10:

There was ……………. so deleted it after re-reading Dave's post.

At least I'm not losing my marbles, ground or otherwise.

Andrew

[SillyOldDufferModerator @sillyoldduffer]

Posted by Andrew Johnston on 05/06/2020 08:23:01:

… May be SoD has more influence than we realise, and we should be careful in case the boys call round for a 'chat'.

Andrew

Absolutely agree. SoD is infallible! My mum thinks he's gorgeous too…

Fantasy over. The claim in favour of grinding comes from Industry taken as a whole. As manufacturing developed over the centuries, every effort has been made to replace toothed metal cutting with some other process. Either because the alternative is cheaper or is more accurate or both. Casting, Rolling, Stamping, Extrusions, Gas Axe, Lasers, Water Jet, Spark Erosion, Chemicals, Forging, Grinding and many more techniques are in the game.

Possibly the forum's deep interest in lathes, milling machines, files and saws leads us to lose the big picture? Whilst 'our' methods dominated industry into the early 20th century, not so today. Time marches on. Not only are more production processes available now, but machinable metals are often replaced with plastics, ceramics, and difficult metals that don't mill or turn well. For that reason manual lathes and mills are rarely found on production lines.

Have a wander round and ask how each product in the home was made and how much of it involved a lathe or milling machine. Take cutlery: there are nearly 8 billion people on the planet and most of them use knives, all made by rolling, stamping and grinding. Many other common objects avoid cutting too. Screw fasteners are rolled. Precision threads are ground. Opening up a printer, TV set, vacuum cleaner, fridge, boiler or even a car engine won't find many milled or turned components in it. Most of my workshop tools are ground, including the lathe's ways and the milling table.

Plenty of counter examples because toothed cutting is still the best way of tackling many jobs, but it's not nearly as ubiquitous as it used to be. Any Production Engineers on the forum?

Dave

[Former MemberParticipant @formermember32069]

[This posting has been removed]

[Mike PooleParticipant @mikepoole82104]

There were a couple of Lumsden grinders in our machine shop but even though they are the king of grinders for material removal I don’t think they would trouble the rest of the machines in the shop for removal rate

Mike

[JuddyParticipant @juddy]

I work for a major engine manufacturer and we avoid grinding as much as possible, mostly due to speed. If you want to machine an engine block every 30 seconds, you cut using edged tools. The only components using grinders are cranks & cams and that's a finish grind for the last couple of microns. Which is slow because the wheel has to be dressed after each journal. So very little metal removal and a lot of dirt.

Modern high speed CNC machines are perfectly capable of milling, turning, boring without the need to grind. Tool changing is automatic and without stopping production which cannot be done with grinding wheels.

[Bill PudneyParticipant @billpudney37759]

Not as esoteric as some and cheaper than most. My two surface plates are ex electronics cabinet de humidifiers, "Warmers",  that were caught on the way to the skip. All traces of heating elements removed, and ground where it matters. They are about 300mm x about 220mm. The height gauge is a metric APE Microball that was also redirected on when on its way to the skip. I've just had a look on the local ebay and they seem to be fairly readily available and quite reasonable. The surface plates are excellent for what I use them for, and the height gauge is consistent, accurate and easy to use.

It's very easy to over think this stuff sometimes!!

cheers

Bill

Edited By Bill Pudney on 05/06/2020 12:14:44

Edited By Bill Pudney on 05/06/2020 12:15:30

[Neil LickfoldParticipant @neillickfold44316]

Well out of curiosity of looking at the new Kitchen counter top, engineered stone. With the light and reflections looks fairly flat. I set up a dti and a plate with 3 point and moved it around the place. The whole area is better than 0.04mm. The majority of the centre area is well better than 0.02mm. So instead of buying a 1m granit plate for the shop,when she is not home, the kitchen top will work just fine. Thanks for the heads up on that. I have no idea how they even get them that good. Not often I am marking out pieces longer than 300 mm. But when needed have ample space as long as it is not heavy, oily or will not scratch the top. Just have to make sure the height gauge base is clean first.

[Ron LadenParticipant @ronladen17547]

Must be my lucky day, on Ebay I put an offer in on a Mitutoyo APE Microball 12 inch height gauge and its been accepted..

Its said to be in good condition and complete with its wooden case.

Edited By Ron Laden on 05/06/2020 12:31:38

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