Hey guys so I’ve been wanting my own reference surface/ flat surface and for the most part I’ve been using a piece of cast iron from my table saw, but when I seen these piece of granite am idea form in my head so use these and this is that process. How I took these piece of granite that where anything but flat and took them to within a couple of hundred microns of absolute flat.
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45 years ago in metrology class we measured a large granite flat plate with optical instruments. It was a wonderful introduction to the measurement sciences which I used throughout my career. What you have done there is an excellent effort to fabricate and qualify your own flat plates - Kudos!
Thanks for the comment and I appreciate the kind words. I do play on making a follow up video on the plate down the line, so keep your eye out for that.
When grinding 2 pieces, the upper piece tends to go concave, as when it overhangs the lower piece, the middle gets ground more but the sides don't get touched. Similarly the lower piece ends up convex. The folks who grind their own mirrors for telescopes make use of this phenomenon to get the correct curvature.
huygen optics channel. the guys a lens making master, hes all about the convexes and flats.
My first thought when I saw the curves, was to have two plates (1&3) on the bottom and lap over both (with 2). Then the two high spots are in contact, and it avoids the issue you point out with the roll due to gravity off the side.
@@deepwaterlagoon You've almost reinvented the 3 plate method, which was the original way of producing surface plates.
Makes sense why surface plates are so expensive, the work and the quality control to produce one is immense. Being a engineering technician i would love to own my own good sized surface plate.
Yeah there’s a lot of work that goes in to making them, and all the R&D before hand. So yeah you’re getting your moneys worth. I always think if I can make it I’ll give it my best shot
If you're in the states, they can be had quite cheaply at industrial auctions... I picked up a decent grade A 24"x24" with a stand for a little over $100
@@tehbonehead That is a great tip and I'm happy for you:) Without wanting to spoil your good mood: The expensive thing is not just the surface plate itself, but the certification or recalibration that you have to do after a certain time (for production equipment). A clean room with temperature-stabilized air conditioning is not necessarily cheap either. And let's not even talk about the extensive and equally well-calibrated measuring equipment and normals/tolerance elements/references. My apologies!:)
I use silicon carbide for lapping granite on granite. It cuts pretty fast, but also breaks down fast. It is not embedding in the surface (compared to Diamond) and you can get it dirt cheap online.
I salute you sir. the ancient Egyptians could not have done better.
Just a suggestion as to what may have been contributing to the uneven lapping results you were getting: while researching to lap a couple of plates myself, I found a number of people saying that rectangular plates are not ideal to lap. This is because when the top plate is 90 degrees to the bottom, you have a lot of overlap which tends to take a lot more off the edges which seems to be what you were experiencing. Square plates are best and when lapping, just make sure the top plate just goes past the bottom to help keep an even coverage. But so long as you are happy with what you got, that's the most important thing. Thanks for the video.
Hey thanks for the comment, yeah you may be right and it could have what made them as they where, when I was lapping them I would push the through straight then at 90 then a figure of 8 doing that evenly, but worked out in the end. I do plan on doing a follow up video and we will have another look at them to see if things have changed. I appreciate your comment, glad you enjoyed the video.
Darren Barclay, I am certain it is enough that you are happy with your results, but I may have a bit of bad news and some good. The bad news☹ - your metric conversions are off by 100x! For a Grade B plate the the limits of 120 & 200 u-in convert to 3.0 & 5.0 microns (u-m). The good news🙂 is that, if you are willing to make a few simple gauge pieces, I can tell you how to measure your straight-edge and surface plates with enough certainty to support Grade A (self) certification (or possibly even AA). Perhaps you could get a "re-do" video out of it. Another good news🙂 is that once you are able to measure and hand-lap your plates to the 20 u-m range, the loose-abrasive plate-on-plate grinding will then work and will assure smoother surface maps. Local flatness variations over various spans can be detected/measured with simple 3 or 2-footed gauges. Here are some links about making and using such gauges for home-made optical flats and surface plates. Note especially the demonstration of flatness detection with a resolution around 22 micro-inches near time stamp 8:30 in the first link - Let me know if you want my e-mail address (or look it up via comp.os.cpm newsgroup).
Thanks Fred for the comment, I’ll have a look at those but yeah I’ll make a follow up video about the plates down the line and we will see if they have moved or if I have to go back over them.
Good work Darren, hats off to you for having the patience to do it.
Great job! I'm going deaf and use closed captions all the time. Half the fun is watching the AI trying to work with the accent. No worries, I know we in the States butcher everything 😊 Glad I stumbled across your channel.
Thanks man and am glad you enjoyed the video am sure there’s plenty you’ll enjoy.
@@Darren_Barclay I was having a bit of trouble understanding you so I turned on closed captions. Unfortunately it made it worse and I started arguing with the computer ;)
@@dennisbjones sorry brother usually the captions are 99% bang on what am saying.
@@Darren_Barclay I was just having a joke mate. Had hundreds of years of experience listening to Billy Connolly.
Great result, well worth the effort.
These DIY surface plates look really good, great job! You have a lot of grit and determination. 👍
Thanks man am glad you enjoyed the video and yeah I always put my all in to these sorts of projects.
Loved this video. People interested in something, thinking "I'm gunna have a go", then having a go. Good stuff. Like you said, it's good for what you're doing. The methodical way you went about it was good to watch. Cheers.
Thanks man am glad you appreciate the effort that went into this, as I only showed a very small portion of what I actually went through with it, never wanted to bore my viewers.
Great job, it's so good to see someone sharing what they can with the resources they have rather than trying to make something perfect. Amazing job though and feel like you can pretty confidently say it's flat!
Thanks man that’s very much appreciated, I do plan on making a follow up video on the surface plate so watch out for that.
That was really very interesting and made me glad I just bought mine. Thinking on your one, two, three plates, I was reminded of grinding telescope mirrors as a kid. The top plate (No2) tends to wear to concavity.
That's such a cool project! There's a series of videos on here of Dobson (Dobson Astro Initiatives channel) giving a workshop on grinding some nice big 300mm(?) mirrors. Really fascinating process, and quite interesting how you use that phenomenon to your advantage.
Wow! I appreciate that you showed us how you did that. It is always easy to spot someone who is smart at his trade, even if they don't have all the best tools, shop or video equipment. Nice work.
Thank you for those kind words, am glad you enjoyed the video, I appreciate you.
This is the first of your videos I've seen. Loved it. Cheers.
Thanks man glad you enjoyed it am sure there’s plenty more you’ll enjoy.
Look like you did a great job , its as long as you are happy !
Well done Darren, you have some patience pal, nice job 👍👏👏👏👏
Nice job.
Having just stumbled upon your channel, because what this vid is about. I've gotta say, Great work!! I like to think I'm pretty clever when it comes to making the tools I might need. Mostly because I can't afford to just go out and buy them. I'm not sure if I'd have come up with or attempted to do this. Outstanding Sir!!
That's awesome, well done! :)
Very interesting and detailed video, nobody can pay you for the work you put into it. The deviations that still exist can simply be ignored for private use. I have a green granite, 500 x 500 x 70 mm, polished to a high gloss, with a deviation of 0.2 mm over the entire diagonal. I'm not going to sand it any further. The result you have achieved is excellent. A very exciting video. Even if it was sometimes difficult for me to follow your accent :).
0.2mm kind of sounds like a lot to me? Though that of course depends on your use.
Darren, as mentioned below, both Tom at oxtoolco and Robin at ROBRENZ made videos showing how surface plates are lapped. Also, at least Robin (maybe Tom too?) emphasized that surface plates needed to be supported on three points to keep them flat. For your uses and size of surface plates, it may not matter how you support them. Congratulations on the plates you made!
Great to hear a fellow Glaswegian ... I'm from Dennistoun myself 😁... as to whether or not they are perfectly flat, yes it'd be great if they were perfect, but at the end of the day you tried to do it yourself 👍 I made kitchen worktops out of 2ft square by 1" thick granite slabs (doubled at edge to 2"), £240 instead of thousands for a 3/4" rip-off version!
great effort and a good result, one has to remember you are not build space parts and what you have done is great for the DIY work shop
Nice work, it's a fun thing to do. You should probably have started off with far rougher grit, I did my plate starting with 80 grit aluminium oxide and lapping with aluminium and slate blocks. Unfortunately, you're off by a couple of orders of magnitude in your measurements. A grade aa plate in those sizes should have a local flatness around 35 microinches, which is about 0.9 microns. 80 microns is about 30 times above what is acceptable for grade B. Alright for rough marking out, but not really good enough for metrology work. For mapping your plates, though, there's a lot of heavy maths involved, so your results are probably better than what you're announcing. FWIW, I managed to get my plate to *about* grade B, which is good enough for what I'm doing with it, I might go for the 3 plate method and aim for AA, but it's a lot of work.
Evenly formed peaks and valleys grooves in the wet mortar going straight across the narrowest dimension would help in getting maximum contact to the tile by letting the air escape as the peaks collapse and the valleys rise all without too much work.
@4:49 - the shiny one after you scuffed it - you could probably sell that as a piece of art! Brilliant video.
I think I will bring my one out to get the sharp edges done I keep catching my hands on it lol xx
Fair play lad! Elbow must think it's 13 again! Respect from D&G
Nice video , thanks :)
Oxtool did a video on grinding a reference plate a few years ago
I’ll check that out thanks
@@Darren_Barclay He actually did a video(or two maybe) on lapping metal plates and he did a video on his granite plates getting reground and certified. ROBRENZ reground a big granite plate of his own using a smaller cast iron plate. Same method used on OXTOOL granite but he did it himself. You worked out the hard way that the granite on granite wasn't very productive. For your scale of workpieces, import grade 3-2-1 blocks and diamond paste probably would have worked ok. 2-4-6 blocks even better. That would be off the shelf solutions. Depends on how much content vs frugality you are shooting for, because a 12x12x2(inch) .0001 tolerance is only $60USD.
@@davewood406 Yeah, the commercial ones are so cheap, it'd be hard to justify the effort other than simply as a hobby project for the fun of it. I'd really like to have a larger plate (my largest is only a grade B 12 x 18), but the price and especially shipping costs go up pretty quickly when you go larger 😕
@@DaveEtchells yeah, I want to say just going up from b to a on msc supply nearly doubles the price.
Never saw somebody actually do this. Very interesting
Thanks man glad you enjoyed it.
At least you have attempted this practically and observed the deviations. The technique is similar to that used to produce parabolic mirrors down to angstroms. From my understanding it's exceptionally difficult to create flat surfaces by grinding 2 against one another as they will always tend to go convex and concave. Usually 3 plates are used, top and bottom are stationary and the center reciprocates. Alternatively you can use a smaller lapping surface to remove high spots
Great work! Have you noticed if the concrete backing makes the flatness unstable? I would initially be concerned that the two materials change differently with changes in temperature and humidity. Maybe not enough to actually be a concern though.
To be honest am not sure about how much they move relative to each other, time will tell, I plan on doing a follow up video so stay tuned for that.
The problem was turning the stone sideways. You were removing material from the center but not the overhang on up and down strokes. That is why 2 had a concave center. There are specific patterns used when there is overhang and you also don't want to push down on the side, adding extra pressure and less in the center.
Gostei da técnica
obrigado, estou feliz que você tenha achado útil.
Really neat project. I wonder if you could have used epoxy to bond the granite to the concrete. I’ve got the cans of abrasive that my dad used to grind telescope mirrors back in the day; they started out really coarse, like 120 grit. & of course they want it to be concave in that application.
Yeah epoxy would probably work and yeah am sure that stuff would work perfectly.
I had a feeling that second stone would cut too much. It was a good idea, but that would really only work for the 3 stone method if they were all cross-hatched like that. Then the method would have worked. Of course, then you wouldn't have a flat reference stone at the end. You'd have to flatten another stone with the 3 cutting stones (and with the 4th stone you'll be knocking them all out of flat, so, probably not the best way to go about it unless your 3 stones are MUCH harder than the 4th). The way mirror makers use the 3 stone lap method is to make a slurry out of diamond powder at specific grits (surprisingly inexpensive) and put an even layer of the polish slurry on each stone as you work them. That way they all cut the same, and even each other out as you switch them between each other.
re: flatness - can you tell the difference betweeen the surface being offset, or the edge being a bit curved (which would point the gauge a little high - still lower, but not as much as what you see on the reader)
Well, I'm making surface plates for quite a while, and I have to say that you can only measure flatness using precision levels. Using a dial indicator with a magnetic base is out of question. Stick in mind that they may only be able to measure local flatness. Of course we use repeat reading gauges to do this.
Yeah am aware and I did state at the end of the video that I wouldn’t hold the data as 100% accurate as I never had the right tools. And I did use a straight edge in combination. So it’s plenty flat for what I do.
Nice work mate! I tried to do something similar and gave up when I couldn't rub down the granite haha. What diamond stone grit do you recommend for course removal? It makes sense to me that cast iron is an easier material to flatten DIY using scraping. Even easier if you can use someone else's as a reference to blue it.
Hey, yeah it’s very tedious work hats off to those that do this full time. I just got my head down whilst watching things on KZhead, for diamond stone I used a 240 grit, it was really coarse. If your going to use diamond stone you definitely want to have other ones that you can work to a finer finish and take all the scratches out, on my no 1 plate there is still a few so maybe a 400 but the 240 work at taken material away fast. Hope that’s helped.
I'm just here for the accent, but great work!
this gave me an idea: epoxy granit under granit
"I got three pieces of granite ..." My first thought was: Hmmm, good idea. I've seen such plates, too. Somewhere ...". So you where on a trip to the cemetery last night, Darren? Hehehehehehe. I like it! Thanks for the video and sharing your ideas. Greetings from Germany and subscribed!:)
lol yeah it was a trip and I appreciate it an hope you enjoy my content.
Doing this leads to having two opposite paraboloid shapes. This is one way of grinding telescope mirrors. The two surfaces will never be flat.
Well done, Darren.. But hard to follow.. Are you from Scotland? Anyway..subscribed and greets from Austria..
Yeah am Scottish, the subtitles usually are 99% of the time correct. But am glad you enjoyed the video and thank you I appreciate it.
Aaaawww sweet a scottsman (irish man) i get to add to my subscription list xD sry im not from the area please dont taks offence if i mislabled just let me know in the comments!
Nice work 👍. 1 micron=0,001 mm not 0, 01 mm 😉
All of the surface plates I dealt with had three "legs" or feet under them to prevent the plate from rocking and to prevent whatever the plate was resting on from warping the plate. They had two feet on one end that were about 1/4th of the length of the plate from the end and also 1/4th of the width of the plate from the two sides. The third foot was 1/4th of the length of the plate from the other end and centered side-to-side. The feet could be hard rubber or hardwood disks about 1/8th of an inch thick and a couple of inches in diameter.
Hey thanks for the comment that’s a great idea as they are a pain to lift.
@@Darren_Barclay It's also much easier to level something on three legs than it is four. You level it side-to-side with the two feet on one end and then level it lengthwise with the single foot. However, putting too much weight on the corners either side of the single foot can tilt it.
I made my omw using the three plate methods and work well, it is the base of all of my precision tools for my homemade lathe I have a small chanel in case do you want to check I will be pleased
Yeah it’s a tried and true method, yeah I’ll check it out and fire you a sub. Hope your subscribed to mines and you find my channel useful at the very least entertaining.
@@Darren_Barclay I subscribed and share with some friend in the WhatsApp group, your method are fairly easy than mine I used just the three plates sequence and abrasive compound, it take me six months to finish it working some hours per days
@@pedroernestobraga yeah mines took me about 60 hours it takes a fair amount of work, but to be fair I used diamond stones to refine it. If I didn’t do that it would probably be double the time.
And thanks I do appreciate that.
What was the degree of flatness BEFORE the "flatening"?
I never measured it, but it was basically twisted, as I showed in the video. The left bottom was high and the right top was high.
Are you not afraid that the shrinkage of the cement will warp your plates out of "spec"?
I guess time will tell, I will make a follow up video about these plates and we will see if you’ve moved. So follow along
@@Darren_Barclay Oh I am sure I will have moved by then. But yes, time will tell, perhaps I end up in a bed, unable to move? Hm.
Does sandstone take away material from granite?
I wouldn’t think so, sandstone is very soft.
@@Darren_Barclay I'm going to verify my offcuts again. If one is off by less than 0.2 mm, I might give it a try. If not, a cheapo is all I need and I can't imagine a better tool investment. As was my Aroma diamond plate for sharpening, years ago.
Great research and workmanship and you should be proud of the surface plate you made,,,,BUT,,,,,You have to have a ton of money in hones and paste and you can get a surface plate that size for like 80 bucks. Seems to me 3 days of your talent and skills could be used to make things like tooling or other things for the shop. (and I'd like to see what you come up with next, like learning to scrap) BTW, In the future, if you want to have complete fill of the concrete put the granite on the BOTTOM with the mud on top and then vibrate it with something like a sander or air chisel. It will shake out all voids. (Get some gout like Sufla-set or like that to fill p the bad places),,,,,,,No matter what, though, that is a hell of a good project and yo should be proud if it. .
Thanks man am glad you can appreciate the amount of effort it took and yeah if I was to do it again I’d definitely do it that way. But I appreciate your kind words.
You are confusing mm with microns. The 8mm you showed is really 80microns. You doing a great job besides that keep up the good work brother!!!
Dinnae ken you could make one.
Someone correct me if im wrong but granite absorbs moisture and changes dimensions, the cement underneath is full of excess moisture. Lapping it now flat means dimensions distorted later.
Maybe time will tell.
One of the reasons they use granite is that it is somewhat dimensionally stable under changing conditions.
I worry that the differential physical characteristics of the granite and cement could potentially cause more internal stresses and instability within the laminations than would have obtained in the granite tiles alone. I'm merely speculating, but it's a concern whenever different materials are bonded together. You may have already been watching them, but I can remember watching some great videos about both the theory and practice of lapping surface plates on the Ox Tools and robrenz channels. For example, they may address which lapping media is best for granite, among other materials.
Yeah I have thought about that and only time will tell and I’ll keep an eye on them, I’ll make a video down the line when we have another look at them. And thanks I’ll check that out.
Don't you face a problem with differential thermal expansion? Why not bond the plates in pairs to provide the thickness you need but without the expansion risk?
Hey thanks for the comment, of course I had taken that into account and I won’t know until down the line. The idea was to do it as cheap as possible and I think I achieved that, and yeah epoxying 2 together would have been even better for stability but we will see down the line, I will make an update video in the future.
Might be ok for measuring but i wouldn't hit on it wirh a hammer, there is a reason they are typically 4 to 6 inches thick! And even they break!
Yeah agreed don’t hit on it with a hammer lol
The granite you are using is too thin, Lapping makes the stone move. The lapping compound in use breaks down within seconds and is nothing more than mudd. I lap plate to plate all the time. It is the very best way to do this but you need the correct diamond compound. I also use a diamond charged 90 pound steel lapping plate but the granite works best as the pores on the granite hold the diamond like a serrated plate would. He has ground polished and finished kitchen grade / type granite. That being said, Even after he gets one "Flat" it will never hold the spec for a grade A or B plate.
Hey thanks for the comment. Yeah I had thought about how thing it is but I’ll I can do now is just keep an eye on it and see if it moves over times, I pray it doesn’t if it does I’ll have to lap again. And I totally agree the right diamond paste is paramount, the stuff I had wasn’t the best. What size paste would you recommend for lapping?
Hey Darren pal, the patience you possess is incredible mate. I think I will have to try adding unleaded to my mix next time 😂
It looks to me like your Grade B plate had a max local deviation of 250 um (not 350)
6:00 - would that hammering add stress- why not just use the granite as a base and poor the concrete onto it? One way to find the place to grind is to blue the surface, where they touch would produce a map of the high points, which can then be manually ground down a bit. - a similar idea to how lapping a surface works.
Yeah could, but the aim of this was to make as flat a surface as possible spending as little as I could, for the time been it’s flat to within a few hundred microns but I will of course keep an eye on it with the straight edge over the coming weeks and months and I’ll make a follow up video down the line and we will see if the granite moves. Thanks for the comment.
your accent is heavier than the granite plates, great video
You from glasgow mate
Yeah grew up there.
Nice to see done but a lot of effort considering you can buy a ready made one of roughly the same size for less than £150.
Hey thanks for the comment. Yeah of course I had considered buying one, but my ethos is when it comes to things, if I can make it in my workshop with the tools at hand, I’ll give it my best shot. Now I’ve got 2 that only cost around £50. It’s easy to buy things but hard to make it, no point going through life always choosing the easy option.
@@Darren_Barclay Fair play.
Not vastly different from some techniques to produce optical surfaces (mirrors and lenses).
I'm impressed by your sticking to what must be one of the most tiresome tasks there is. I get bored lapping in smoothing planes !
Yeah after 2 days I was fed up and my arms felt it but I just kept in mine what I was hoping to accomplish.
Wouldn’t it have been better to put the granite face-down in the bottom of the form and pour the concrete on top?
Hmm maybe either way work I guess.
@@Darren_Barclay just think it would help mitigate the voids under the granite slab.
There is NO way ,using a piece of ordinary Marble or granite is a even close suitable replacement for a PRECISION surface plate !! lol NO WAY unless your working with "wood" ... I am a retired toolmaker for over 45 years . There is NO substitute for an "Inspection Grade" Granite "CERTIFIED" and Calibrated surface plate .... Sorry : (
Then just what kind of granite are surface plates made of then? I can see the sign- "Special surface plate granite quarried here" - FACT!~He is WAY under a couple of tenths TIR so what is the big deal? Do you actually think he has any machines in his shop that can carry .0001". - HEY, Tool and die maker yourass. A certified cork sniffer is all you are. - BTW, I am a millwright contractor (The guys that scrape in the ways on your surface grinder and the journals on the centerless. OH,,,, got my engineering degree form OSU in 1980. You may be retired for the last 45 years, but I'm betting you were nothing but a 3 month apprentice back when you left the trqade.
I hope @OXToolco sees this!