Making Flat lapping plates 4

In this video we begin to prep the copper penny laps. These laps will lapped together using the classic three plate method to generate perfectly flat planes. The surface will then be "charged" with diamond abrasive to make fixed abrasive type laps. We also answer some viewer questions and comments, discuss monochromatic helium light and some very large radii.
Link to cast iron raw material used for laps.
www.mcmaster.com/#8588T23
Loctite 380 Link,
www.mcmaster.com/#74555A65

[@kirillkirillov3809]

One of the mine maths teachers said: "Straight line is just an arc of a circle that has infinity radius"

[@car9167]

Most likely there is nothing like a straight line in the whole universe with all the gravity and action at a distance. It is only a concept in our mind

[@RFC-3514]

@@car9167 - You might argue that real space isn't perfectly Euclidean (though in most contexts it's close enough that it's impossible to measure the difference), but any line that follows the same curvature as space is technically a straight line. The ones in my mind are all crooked to begin with, though, because I don't like to set myself up for disappointment.

[@ravener96]

And as we see here christian is struggeling with abstract concepts. Cute

[@JoAkh]

This is interesting to think about it. A straight line is what we see or imagine but even if we look at a precision ruler for example it's not actually straight. There will always be a micro difference. And this is for everything around us.

[@joshmyer9]

Tool for filing, Mozart for lapping: truly, Tom is a man of eclectic tastes. (This whole series is making me want to order three Pyrex blanks…)

[@michaelgriott3922]

Josh Myer Yes, the man who calls himself "The Ox" is in fact an intellectual machinist!

[@FrBobLaceySD]

Josh Myer Thomas Aquinas, a man of incredible theological genius, was called "the dumb ox"! Fitting.

[@calinguga]

@@FrBobLaceySD no such thing as a theological genius

[@thegeneralstrike6747]

Being eclectic myself I can feel silver and long ago stashed portholes urging we work together and bring the vast distances surrounding us a bit closer and possibly more importantly closer to those who have little idea just what can be accomplished with a few old scrapyard finds and some handed down knowledge.

[@nicklimuti5186]

​@Călin Guga Theologists don't necessarily need to be religious, religion is their area of study. Having a deep understanding of religion doesn't mean you believe in it, nor does religious belief mean you are unintelligent. Most of the most important scientific and mathematical discoveries in history have been made by religious people. Just the observations of a non-religious guy of average intelligence.

[@SyBernot]

Thanks for doing that Q&A, The only question I still have in my mind is: You have them flat how could you make them parallel? That's just mostly me thinking out loud, I realize they don't need to be parallel. After watching so much of your channel, ROBRENZ's channel and David Richards' channel I've rediscovered my love for this sort of work I've decided once I retire from what I do now I'm going to go back to the machine trades, at least as a hobby. Every day is a learning opportunity.

[@sjwsbetaskiller6218]

Making them parallel is a very next (higher) level. I doubt you will see it on KZbin.

[@parkermusselman9824]

Awesome series, thank you for putting this foundational stuff out there. I may have already mentioned it but I would be really interested to hear more about putting a new lap to use and how to keep it flat.

[@michaelgriott3922]

As usual a superb, articulate explanation of technique as well as the physical bases for it. I also agree that the classical score is the perfect accompaniment for such fine work!

[@lookcreations]

Thoroughly enjoying this series, very much appreciate your explanations of process. "The Magic òf Averaging!", that's going to stick in my mind. All the best Mat

[@brucewilliams6292]

Thank you for the great explanation on why you did what you did and remembering some of us don't have a surface grinder ;) .The commentary is the most important part of your videos. Thanks for the follow up.

[@miles11we]

"Nanometers are dinky, ok?" - Tom Now thats a tshirt

[@BasementShopGuy]

This is a great series, Tom. Really enjoying it and I totally get the "journey" part of it. Putting in the time and elbow grease is what separates the Joe's from the Pro's.

[@sjwsbetaskiller6218]

Mediocre chumps/hacks will never "get it" (they complain this series is too long).

[@douglaslodge8580]

..The desire to excel in craftsmanship should be uppermost in your thoughts. So, while you are building your model coach, think only of making it the finest piece of work you have ever produced. The praise of your friends and recognition by the Guild will take care of themselves if you have done your work like a real craftsman. If you adopt this attitude toward your work, you will be surprised how much easier it will seem and how much more pleasure it will bring you. Think of the fun it will be to make each little part of your model a masterpiece in itself, and then to fit each into its proper place and watch the solid, handsome coach gradually take form. The surest way to get the greatest rewards from your work is to keep the ideal of fine craftsmanship always before you. This is not my quote. It was given to the student competitors in 1932 for the Fisher prize sponsored by Fisher Body. I see this in your work and the work of your community on You Tube, Abomb 79, Keith Rucker, Keith Fenner, mrpete222, Clickspring, and many more on a list that is to long to list. I just wanted to say Thank You.

[@jimzivny1554]

Great series, thanks for taking the time, I'm learning!

[@douglasheld]

Tom, thank you very much for your three video series. I am going to follow this technique to make two (even though I only need one :) really flat plates!

[@KingNast]

Come on man, I want you drive us straight into downtown nerdville. We can handle it

[@zach7375]

That's pretty awesome Tom! Very informative.

[@mog5858]

nice work. i like how you talk about how to get somewhere and why rather than just the fastest way to point b from a. keep up the good work.

[@donaldmccaffrey7992]

Tom, thank you so much! You are a great teacher.

[@TarmanTheChampion]

I have no idea why I'm watching this.. but it's so interesting! I cant stop OR change the video!! Thank you for all your hard work! I had to subscribe!

[@Jay9999]

Great video series👍 I learned alot, Master Jedi Tom.

[@trajtemberg]

Loving the journey Tom.

[@JBlanke]

I love the music playing in the back, it was very nice and peaceful watching you while listening to that.

[@ramosel]

I too like the classical stuff but prefer the days he plays TOOL!!!

[@1jtolvey]

CLASSICAL = THE BEST " WHITE NOISE " KNOWN TO MAN ! LOVE IT .

[@bigun447]

Ditto on the music. That is what is always playing in my place. Keeps the mice at bay.

[@KnolltopFarms]

Another great one to have as background music while working on something you need to think about is Hawaiian music. This was told to me by an old Master Carpenter named "Woody", best I ever worked for! He said "You don't really listen to it, you just hear it, since you can't understand the words". He would never let us listen to Rock because we made mistakes when "Rockin' Out" and singing along. He was right.

[@EverettWilson]

Knolltop Farms I love almost any music in a language I don't understand for exactly that reason. Instead of listening to the meaning of the singing, it's reduced to an instrument.

[@laulabansen1307]

Thanks, I study tool and die making and your videos always deliver great insight.

[@Rolexor]

That’s beautiful. Thank you, Tom.

[@TheMadJestyr]

"Nano-meters are dinky, mkay."

[@SOVEREIGNDesigns]

Very Cool ~ Was noticing the refraction on the plates before the Schooling on lighting

[@RRINTHESHOP]

Just wonderful. Thanks Tom.

[@proinnsiasoc]

Brilliant Tutorials for Lapping these discs. Watched all 4 videos just now consecutively . Looking forward to seeing the result. Flatness , squareness and roundness are the 3 vital components of accuracy and producing these laps is very interesting . Oh the classical Piano at the end is bordering on ostentatious :-D :-D . Great stuff.

[@justinwoodlee1062]

Those blades do great. I got one and used the heck out of it and it's still going.

[@vincentgizdich2842]

What kind of material have you used em for? Used it on what tool?

[@ROBRENZ]

Nice work Tom, looking forward to seeing some parts lapped. ATB, Robin

[@garyc5483]

Thanks for sharing Tom. A quick Google found this:- According to Title 18, U. S. C. section 331, it is illegal to "fraudulently alter, deface, mutilate, impair, diminish, falsify, scale, or lighten any of the coins coined at the mints of the United States, or any foreign coins which are by law made current or are in actual use or circulation as money within the United . BUT it says nothing about altering coins for personal, experimentation or artistic use. I think "fraudulently" is the operative word here. regards from the UK

[@AlexanderGee]

No deface is the operative word. The coins are literally being defaced. Still no one really cares

[@stickyfox]

@@AlexanderGee Not at all... this would make souvenir pennies illegal, and that's the example that's typically used to refute this argument. The treasury has issued very explicitly worded statements including this example to explain that fraud, not altering currency, is the crime. Additionally, laws were added in 2007 (31 CFR 82) to prevent melting down nickels and pennies specifically for the purpose of recovering their metal value. It's always been legal to use US currency to make jewelry or sculpture or scientific instruments. *It's our money* anyway.

[@shanek6582]

I'm so happy, today I went to a yard sale and bought for $15 a big Jacobs chuck with a 1 1/2 - 8 thread on back that fits on my craftsman lathe.

[@fermorales9087]

Thanks man. I love this stuff.

[@63256325N]

Very informative. Nicely explained. Thanks.

[@stevelalondejr2183]

So in he end the flatter the better even if you have to walk a few kilometers to get there. I think this is very interesting being a machinist ,keep up the info videos !!

[@TFOAustralia]

keep up the great work Tom! love your vids , very helpful could you please upload more often ;)

[@davidaarons2488]

Hey Tom. is coming along nicely. Just want to say that you doing it this way is so us hobby guys that don't have or access to a surface grinder, can have a awesome lapping plate. Thanks Tom for showing this process. I think would use Pink Floyd instead of that classical music. Just me. God Bless Ya Dave

[@verdatum]

Random thought that entered my head: "Mommy, when I grow up, I want to be an optical metrologist." It actually sounds like it could be a pretty fascinating field of work...

[@JourneymanRandy]

Good stuff. Thanks Tom

[@mike-synthetica]

Cool series!

[@OfLastingThunder]

When spinning the top plate the music synced up and it was soothing.

[@bcbloc02]

And I thought chasing .0001" was fussy work then Tom takes it to the next level! I suspect Tom has a new angle for the 4 jaw contest at the bash, the new criteria is whoever dials the fastest to within 20 millionths wins. You have to use your own indicator. :-)

[@gresvig2507]

Great series, and thanks for doing it. I'm going to try to make some plates as well, and my goal is to lap some Gage blocks that I have that were sent (big QC error, but it ended okay) incompletely lapped. Fun project, I thought. Side note, I'm liking that Lennox disk-- the kerf is wider than you'd think, but it's easy and nice to use (with an angle grinder, at least). Slower than the usual abrasive wheel, but the unchanging diameter is great, and the removal of the ever-present disk grab and explosion hazard makes it a winner in my book. Buddy of mine had an artery cut in his wrist and nearly bled out because of a shattered abrasive disk, and ever since I've been insanely paranoid.

[@CafeenMan]

"The magic of averaging." I'm gonna remember that one forever because it's true.

[@renee46]

Your doing a great job thank you

[@ianboard544]

This is so similar to grinding telescope mirrors. I did the same thing as the copper penny thing, but used stainless steel washers, backed with dental cement.

[@DaleKallio-jk9wo]

What a wonderful demo surface. ..not a lot of loading between lapping components and an angular reference for accuracy in progress👍🏻

[@snoozinglion8596]

Good stuff... Thanks for sharing ;)

[@alaricbergeron4687]

Hey Tom, Just when you were talking about the rigidity of the cast iron plates, I couldn't help but think about the layer of loctite/adhesive between the pennies and the aluminum backing plates. Isn't there a risk that under pressure/temperature changes/time there might be movement of the pennies relative to each other? Probably minimal, but that could be significant at the 150nm scale.

[@kundeleczek1]

Pennies aren't contacting with plates only by loctite but also by themselves.

[@martineastburn3679]

People tend to forget that Diamond is Carbon. Iron/Steel that Ferrous material absorbs Carbon and absorbs diamond. I used to facet sapphire and used diamond laps. The laps were AL. For heat and not to mess with the iron. We were told not to grind with the laps any steel or iron. We used wood sticks and hard wax. Our laps lasted. We used grit when grinding other stone between two cups at an angle to make 'balls'. I did one in obsidian glass. Use lots of coolant when using diamond and steel.

[@anchorbait6662]

I tried drinking everytime you said "ok". Thas was fiftan minutes ago and now I'm drunk

[@stevengabriel8406]

I did a double shot for "mmm kay" as well, and am on my way to the hospital for alcohol poisoning now...

[@TABE-O]

Hannibal Lecter music in the background. Lol. Awesome. Thanks for sharing

[@darklordofapathy]

If your platen was 172mm(6.79in.) diameter you could perfectly fit 62 pennies in it; or 156mm would fit 50 pennies.

[@intjonmiller]

darklordofapathy THANK YOU!!!

[@cofffeymachineworks1181]

Been waiting on this video Tom, enjoyed it. and my wife thinks the penny idea would make a good decoration. go figure.

[@douglaslodge8580]

I really like this video.

[@billdlv]

Good stuff Tom. You hinted at more discussion on the light source, I look forward to that. I'm thinking that it would be fairly straightforward to make one using LEDs as a light source.

[@yanwo2359]

Thank you for saving me the time to write a pedantic comment. Wait. I just spent the same time writing this. Can't win. :)

[@klaper10]

hmm i think if You started gluing pennies/washers from inside it would give nice honeycomb pattern but with more overhang but it was not the problem since it was trimmed on lathe anyway

[@intjonmiller]

Every week that goes by without seeing another episode makes me a little sadder inside. Hope all is well and I can get my fix soon. (And, of course, I realize there are much more significant things than my viewing habits.)

[@Justinofalltrades1]

today i learned that things can be dang flat but not dead flat

[@sjwsbetaskiller6218]

These are theoretical/philosophical concepts (straightness, flatness, etc.). What you consider "flat" (or straight, smooth, round) enough, depends on application/industry.

[@artgoat]

It's easy to tell which penny is which. Drop it on a hard surface. The fully copper ones have a nice ring, where the zinc-cored pennies sound dead. Also the copper ones weigh around 5g, where the zinc ones are only about 3.5g. For cleaning pennies. Ospho does a SUPER job.

[@PeterWMeek]

Great project! We may disagree on some technique, but _ipse dixit_ - the results will speak for themselves. If you get them flat all over to a quarter wave, it will be as good as what the method I have recommended usually aims for. And fast forward through the interesting part where you trot out the numbers? Not likely!

[@sw8398]

I really enjoyed the 4 series of these...one of the other reasons diamond powder and paste charge cast iron is that CI is porous, and hence thats why its so good for dry lapping, the charge gets in there good.....but as you note not to used in facing or conditioning a plate.....for a finished CI lapp, they are easy to charge with Diamond powers, a carrier and a roller bearing..you could even divide a block up four sections and charge with different grits...

[@aajpeter]

If you're going to clip them anyway, is there any reason not to do optimal packing in a hexagonal pattern?

[@johnm840]

I was thinking about that as well, probably not needed but would look better with symmetry. Have to do some Cad work to see. Be a nice Math problem to maximize surface area. Smaller Radius parts would lead to that. something to mull on.

[@TechTomVideo]

the idea of rotating the bottom plate too is that you otherwise have strokes in the same directions on that all the time. you are correct that you rotate the plates relatively to each other, but here comes the thing of the post in the middle of the room, you mentioned in an earlier video. if you walk around that post, you "rotate" the bottom plate relatively to your back and forth motion. if you then rotate the top plate in your hand, you have what the commenter mentioned: a rotation of the plates relatively to each other and relatively to your main motion direction.

[@Giblet535]

Comes a point, the size of the specimen's molecules and molecular vibration become the limiting factors, not to mention temperature variations in the surface. See? My parents said I was why there could be no nice things, but *science* is why we can't have perfect things.

[@edgeofeternity101]

Another note, you have to watch the Starrett centerfinder 45 degree heads, they are not equal lenght on the ends, and have a hand radiused end, and if you get out onto the end past the ground flat, they are no longer a true center.

[@terminalpsychosis8022]

Can almost imagine the distance required pushing back and forth to lap these triplet plates "flat" is about 100 miles too. That radius idea is fascinating. Nothing can ever be PERFECT, but yowza, prety damn flat is right.

[@Kettletrigger]

Great job Tom, I'm really digging this series of videos! I know it doesn't fit in with the self-proving 3 piece process, but I remember reading about a "ring lap" used to flatten a concave lapping plate. One of Guy Lautard's books maybe...?

[@evildrome]

That's what that is! About 10 years ago I went to an auction of a company who had a dozen or so large lapping machines and I picked up a ring off one of the machines which was about 10" across, maybe 1 1/2" tall and 1/4 thick. I thought it was one of the parts they made but I now realise it was a conditioning ring.

[@humanistwriting5477]

I owned some for my lapping machine! Run up to three rings slightly smaller then the radius of a powered lap. They will level the wear from lapping. Up to two can be ran as you lap in a lapping machine. Other desogns include huge rings that run through the center of the lap, and other methods include over lapping lapping plates. There is a noticeable danger of creating a conical lap.

[@carlcrott8582]

Your statements on convex or concave stirred my thinker a bit. Surely thats a function of the diameter of the lapping plates as well as the distribution of the polishing compound. If these are safe assumptions, perhaps the binary of "convex or concave" could be controlled a bit more by designing the physical polishing movement to increase the 24 mile radius to something closer to 100 :D It also makes me think of the movements of orbital sanders, something like a dewalt, which have surprisingly complex movements about their axis. Brilliant video!

[@holmesjustholmes9412]

I'd say it's the magic of symmetry.

[@k.s.1871]

Thanks for clarifying the "theory" behind the 3-plate method of surface accuracy . I always found it quite strange in spite of the empirical evidence .

[@huflungwun5558]

Hi Tom, many years ago I made an 8 inch reflecting telescope. Grinding the mirror was almost the exact same process you are following. The difference was of course I was aiming for a circular then parabolic finish. In the final stages of polishing the two blanks would often stick together and it was a hell of a job to get them apart. Do you get the same issue with the flats? For info, making the mirror took about 60 hours of grinding/polishing. Accuracy was about 3 millionths of an inch, a fairly ordinary figure.

[@jpmorgan187]

Do you have any more info on the reflection telescope and how you made it?

[@johannesschuhmann229]

Thank you Tom for sharing this with us. You probably could also use this method to flaten your oilstones. Just take three of the same grit and hardness, put some oil in between and do the three plate method. You will hopefully end up with precision oilstones without the need of grinding them with a diamond wheel on a surface grinder. I don't know if this works... Just thougt about it recently. Greetings from Germany

[@oxtoolco]

Hi Johannes, You are quite right. The hard part with oilstones is actually measuring them. You can use an indicator but you have to be pretty careful not to wear the tip out. Thanks for the comment. Cheers, Tom

[@wongelfski4681]

Cool, this is how telescope mirrors and flats are made

[@pierresgarage2687]

Hi Tom, Great discussion about going into the micro fine finishes, abrasives and flatness, I'm picking up good info with this... Cheers, Pierre

[@sjwsbetaskiller6218]

That shows, how uneducated "KZbinrs" are, in general. Yet, with incomplete set of knowledge/skills they are "on the mission" to "teach" others, like they are "authority" or something. This is epidemic in the internet. The best machinists/tool/die/mold-makers don't have the time to fuck around and make videos.

[@intjonmiller]

SJWs & Betas Killer The horror that people share and teach while learning. What is the world coming to?

[@pierresgarage2687]

If we had to wait for only 100% educated people to share their precious knowledge even schools wouldn't exist, a good discussion initiated by serious people will often light up a good idea and progress into a path forward to better ideas and products... ;) ( Another reflection, do 100% educated people really exist...??? )

[@gatekeeper84]

Hello Tom, an alternative to the white vinegar in the copper cleaner would be citric acid. It works just as well, has no smell and can be bought (and stored) in solid granules. I get mine from the Asian supermarket.

[@beachboardfan9544]

Is this like making lenses, where the top one always winds up being the concave one and the bottom the convex?

[@boblewis5558]

Your description of the radius of the curve involved in tiny differences equating to 38km gave me a thought! Maybe you should demonstrate to the Flat Earth crowd that something that is scientifically "Flat" actually isn't, so when you translate that UP to the size of the Earth "perceived" flat just DEFINITELY isn't. Ergo even if they think the Earth isn't a globe, it is NOT flat! 🤔🙄🤣🤣

[@evilinme1]

I was really hoping for a part five.

[@trollmcclure1884]

when you have a surface plate all you need is those 3M lapping sheets and you can go all the way to 0.1 micron. Or start on glass and use it for the finish

[@duobob]

Great music for getting into the lapping zone. I might try something like that for scraping. Currently using as quiet as possible. Repetitive work is only tedious if you let it be...

[@noneofabove5586]

Thanks Tom

[@AF6LJSue]

A copper penny when dropped on a anvil sounds different than a zinc copper penny..

[@ritaloy8338]

A Copper Penny weighs more than a Zinc Copper Coated Penny.

[@mikesradguitars]

Thanks so much for this and all your great videos, super informative and fun to watch. I’m desperately trying to come up with a system for lapping plane irons and chisel backs, anything based around sandpaper rounds (dubs) off the edges so when you go to a stone it doesn’t abrade at the edges where I need it. I’ve seen in the world of lapidary they use a rotating lapping plate with an abrasive slurry, like hand lapping under power seems like? So here’s my question: if I glue a bunch of pre-82 pennies to the platen from an old disc grinder and face them off, then use some kind of arbor to spin it, would you expect that to make a decent initial lapping machine? From there I can go to oil stones or diamond plates or something flat. Thanks in advance for your consideration, I really like your videos.

[@thegeneralstrike6747]

Truly excellent playlist!! I have really enjoyed and taken some of this process for use in my own endeavors. This process is proof positive that despite the supposed technological advances made, historically humanity has possessed not only greater protean knowledge but, also the greater overall ability to use the knowledge with some level of skill. The case I would make for today is that the technology is possibly less useful, less efficient rendering it wasted despite or perhaps because of the exceptionalism indoctrinated into the nehscient by the ignorant or narrow of minds. Could it be that it is the experience of setting ones own parameters to achieve a goal in essence a sort of earned freedom through wisdom? A freedom few know today the ability to draw upon experience, form a process and achieve a goal therefore legitimizing ones authority in that broader craft? I have personally experienced some of the most meaningful achievements by using a method rather then an set of instructions. To say another way the master is presented internally or externally with a goal. If one is truly an authority within a craft it is not the method that will legitimize that authority. It is mastery to use any number of methods to achieve the goal. When I choose to achieve those goals by my hand rather then going for a power tool or setting up a machine I find more that the product of my hand was more efficient effective and overall more satisfying. I would chalk any challenge to working with ones own hand having to do with modernity inability to suffer and in turn reap the benefit of growth for that suffering.

[@MakinSumthinFromNuthin]

If you need a few rolls of pre-1970 pennies hit me up, all are uncirculated Cheers~MSFN

[@roguetrooper70]

Right, right right......right..ahh right!

[@karcinoma]

DANG flat. You had better get that on a tshirt lol.....

[@RaysGarage]

Great series Tom, very educational and informative even though you lost me of few times there but I think I'm on board again!

[@sjwsbetaskiller6218]

These are very basic things. It shows how uneducated KZbinrs are in general, but guys like you think you can school people how to do things properly. This is epidemic. Wanna-be "teachers" with incomplete set of knowledge/skills.

[@georgepatterson69]

another interesting series thanks Tom. Just curious have you ever checked how flat you can get a part just by putting abrasive paper on top of a surface plate. Im sure this must be the most common method used by home gamers

[@bobandres5559]

Thanks tom, always a pleasure watching.

[@stevegibson3113]

Great videos - What would be a good range of micro paste grades to purchase to start with? For example, I see that I can buy increments from say 0.25 micron to 40 micron, but do I need them all or could I skip a few and still have a good range?

[@JaczSolar]

Thanks for filming this. I'm not a machinist, but this video series was fascinating. The abrasives part was particularly interesting. You mentioned that the abrasive you chose breaks down as opposed to diamonds -- if the abrasive becomes finer and finer, why doesn't it leave a mirror polish now that the surfaces are so flat? Does it just scratch and break down too fast? To get to the polish for the light test, you used a different abrasive.

[@BenKloos]

Quick tip for separating zinc from copper pennies. Instead of looking at them drop them on a hard surface. Zinc pennies ring copper thud.

[@johnferguson7235]

I think you have earned a honorary membership to the Flat Earth Society. I'd be interested to find out how flat is the surface of a pan of mercury and compare that to the plates when they're done.

[@paulstovall572]

You mentioned that there was different methods of charging the laps, may I ask what those are? Thanks for posting these videos!

[@ianlongfoot4672]

I just have a comment a question and a tip if that is ok. First, you should know by now that no matter what you do in your videos there will be at least a dozen "experts" who know better and will tell you that you are doing it wrong even though you have explained fully why you are doing it. My question is, I thought that heat broke down the strength of super glue so would it not mean that the copper will fall off when being used or does it take a lot more heat than what is being created? Now finally my tip, The best thing I've found for removing the "patina" from copper coins is cheap cola. In my experience the cheaper the better, once I realized what that stuff did to copper I immediately banned it from my house! A great video Tom thank you very much for sharing your obvious skills and experience.

[@siggyincr7447]

Not to claim that soft drinks are good for you, but your stomach acid is far more corrosive than any soda.

[@hands-on-eyes-on9029]

A story about famous geniuus, inventor, and machinist, Hiram Maxim and pennies... 'Maxim was an eccentric and boisterous individual with a tremendous capacity for hard work. He also had a mischievous sense of humour. When his young son longed to own the dog belonging to the owner of a nearby drug store, he was promised he could have the dog only if he paid for it with a double-headed penny, so Hiram junior insisted his family search their loose change for this imaginary penny, however the next day Sir Hiram went to his works, took two pennies, sliced them in half and soldered them together and carefully burred the edges, so that he had a penny of the right weight and feel, but with two heads. The store owner was shocked and puzzled, but still refused to hand over the dog. Hiram Snr had achieved what he wanted, to cause bewilderment and amuse himself. '

[@tonydevich7937]

Sweet

[@tonyashgrove9512]

Hi Tom, very informative, so we can make and maintain our lapping plates, I am NOT criticizing you, but I have to mention in the UK and territories under our Monarchy is a Treasonable Offence to 'deface a coin of the Realm', I don't want anyone getting thrown into the Tower of London, maybe you should mention to check on your Countries regs on coinage!!. Have you tried old Cola drinks to clean copper? they seem to work quite well, but don't know if they get everything off

[@motorbreath22]

Thank you for taking all the time to film and edit this, I think that NYCNC due showed that even when you think you ground something flat it's probably not as the grinding pressure will most likely not be the same along the whole stroke of the work piece, you would need very slow traverse speeds to keep grinding pressure low and then you run into heat issues from rubbing, and you have to hope that your wheel wears evenly depending on how you are grinding, along with going to smaller (higher) grit size or higher hardness or both, or you could do what you are doing and know they are coming out flat.