Cast iron laps - correct depth/spacing of grooves? - Page 2
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  1. #21
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    I found a slitting saw in my collection, 20 carbide teeth, 2mm wide, 60mm diameter. I think I'm going to try that at about 500 rpm, cutting a 2mm x 2mm slot. At 400mm/minute it's about 0.04mm = 0.0015" per tooth, I can flood cool it, each 250mm pass will take about 40 seconds. I'll report back here with some photos after I've done it, need to finish another couple of projects first.

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    Quote Originally Posted by jz79 View Post
    from my limited experience making these:
    Attachment 307115
    (20mm on center and 1.5mm width, 2-3mm depth, using bandsaw)

    initially I was trying to take off a lot of material (hardened steel plate, HLV-H dovetail top), and the narrow/shallow grooves would clog up quickly and make it difficult to generate the pressure needed to actually cut the part - that was with the coarse diamond grit (40 micron)
    once I switched over to 10 micron or less diamond it stopped being an issue, but still seemed to hydroplane

    if I had to redo it, I'd cut the grooves even deeper and increase width to 2mm also, maybe reduce spacing, 12-15mm you planned sounds about right

    from what I understood searching and reading about these is that the small grooves and large flats are essentially for finishing small parts, when you're lapping something larger than the lap itself, increasing groove width and reducing land size makes it easier to generate more pressure to cut material quicker, probably not an issue if you're taking off just few microns, but still, 1mm depth sounds too small
    Curious to know how you set up the bandsaw to do this so nicely. Also where is a good source for lapping paste. Lastly you speak real good english for a Latvian.Were you born in Latvia.? Sounds like a country that would have no shortage of Butt ugly machine tools all built like russian tanks.

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    Bandsaw is a roll-in type, Marvel series 8 mk2, held the plates in a vice (tilted on its side) and used a ruler to offset it for each cut, rotate 90 degrees and repeat, it was quick, but, as I said, I should have used denser pattern for the width of the groove I got with that blade, but the plates did the job I made them for

    regarding old USSR iron, the good stuff isn't on the market, if you ask someone who has anything - the prices are mostly unreasonable for the condition those tools are in today, right after the collapse there was plenty of good stuff around, but that time has long since passed...

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    Quote Originally Posted by jz79 View Post
    regarding old USSR iron, the good stuff isn't on the market, if you ask someone who has anything - the prices are mostly unreasonable for the condition those tools are in today, right after the collapse there was plenty of good stuff around, but that time has long since passed...
    A little thread drift - what's your opinion about the state of Russian manufacturing now? We know that China has been developing their manufacturing resources for decades, and in many cases have truly "state of the art" facilities.

    I don't get that sense for Russia, but it could be due to not having an adequate understanding of the Russian economy. Do you have any opinions on the matter?

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    I find it amazing that in a country like mine(S Africa) there are quite a few Eastern European machines still floating around and are still going strong. Tos comes too mind .
    Do you have problems getting engineering stuff in Latvia . Is there a strong well established market for tooling or is everything a hassle to obtain. ? Where did you get your lapping paste ?Ebay doesnt always deliver to Africa.
    Im still curious to know if yu are born Latvian because your english is just too good.

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    were getting too OT here with this...

    This is second time here that someone is asking about my English language skills, I was born and raised here, never lived abroad, learned spoken English from watching tv in the early teens with a vocabulary in one hand, learned Russian the same way before that, with the exception of parents being my vocabulary (learning Russian was mandatory during Soviet era for everyone), 99% of what I read and watch is in English, worked for couple years in an English speaking environment, but by that time expressing myself in English didn't require translating what I wanted to say in my head, I was already thinking it, Russian is the same way for me, though it is getting rusty, I think this is mostly due to grammar - the structure of the sentences being the same in my native language, English and Russian, words are different, but the way you construct the sentence is basically the same, it has been much tougher with German for me, now I wish I had payed more attention to it when I was younger, much easier to learn diverse things for a kids brain compared to an adult one...

    We have no problems getting tooling around here, couple local distributors can get you stuff in 1-2 days from Germany, then there is some new old stock left over from Soviet times still, not a lot, mostly small things, drills, reamers, etc., new diamond tooling comes mostly from Poltava, Ukraine, couple local places have it, there is some left from Soviet era also, and the funny thing is - this old Soviet diamond paste is much more saturated with diamond than the new ones, Poltava is comparable, but the stuff I have bought from China doesn't even come close, it almost feels like there is no abrasive in it when compared to Soviet era and new Poltava products, you might try messaging ebay sellers from Ukraine selling it and ask about shipping, but due to this pandemic situation, there are quite a few restrictions now on what and where can be delivered even if the seller would be willing to deal with you, DHL might be an (expensive) option

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    I got some time to work on this today. I'm cutting grooves 2mm (0.080") wide and 2mm deep with a carbide slitting saw, 63mm diameter, 30 teeth, running at 400 rpm with 250mm/minute feed. This leaves really clean sharp-edged slots. I did the first plate on the mill table:





    but I don't have enough y motion (just 200mm) to do it all in a single pass (plates are 250mm diameter). So I needed to rotate and realign the plate 4 times, which took more time than the cuts. So for the second and third plate I am doing them on a rotary table where it's trivial to rotate 90 and 180.





    The second one just took a bit more than an hour. I'll do the last one tomorrow, then can start lapping.
    Last edited by ballen; 12-27-2020 at 11:17 AM.

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    Quote Originally Posted by Homebrewblob View Post
    2 Quick questions a lil OT. I have 12”h x 12”w x 1” and 12x12x3” cast iron slices both square.

    I want to make a 12x12 CI transfer plate using my surface plate (and lots of practice).

    My questions were. How thick should my cast iron plate be.
    And what grade surface plate should I use, I was thinking 18x18 AA? Or should I just go grade A
    Where did you get the rectangular cast iron slices? I have been looking and all I find is round...

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    Rimcanyon, I assume you considered dura bar? From memory, I think 12.5” square is a standard. Have found their distributor surprisingly helpful to me for small amounts.

    L7

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    Quote Originally Posted by lucky7 View Post
    Rimcanyon, I assume you considered dura bar? From memory, I think 12.5” square is a standard. Have found their distributor surprisingly helpful to me for small amounts.

    L7
    Yes, but where can I purchase it? The only distributor listed in California is Jorgensen Steel, and they do not list it on their website. Also, the durabar website lists availability as 72" lengths for the size I need, and I only need 14".

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    I’ve purchased from a Canadian distributor in Edmonton. Not much help to you, but if I can get it here, I’m sure an email to their Illinois office would get a reply or forward to a seller local to you. And they do custom saw to your length.

    L7

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    Quote Originally Posted by ballen View Post
    I got some time to work on this today. I'm cutting grooves 2mm (0.080") wide and 2mm deep with a carbide slitting saw, 63mm diameter, 30 teeth, running at 400 rpm with 250mm/minute feed. This leaves really clean sharp-edged slots. I did the first plate on the mill table:





    but I don't have enough y motion (just 200mm) to do it all in a single pass (plates are 250mm diameter). So I needed to rotate and realign the plate 4 times, which took more time than the cuts. So for the second and third plate I am doing them on a rotary table where it's trivial to rotate 90 and 180.





    The second one just took a bit more than an hour. I'll do the last one tomorrow, then can start lapping.
    SWEET !!! Super job by one of my friends who is a perfectionist!!

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    Quote Originally Posted by Richard King View Post
    SWEET !!!
    Dear Richard, thank you, and Happy New Year! I still haven't gotten to the lapping part yet. Was planning to start with Timesaver green fine in some kind of carrier fluid, but not quite sure what to use. Was thinking kerosene might be a good choice, or maybe some spindle oil. Suggestions, anyone? Cheers, Bruce

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    Happy new ear to all of you too
    About the diamond in Russia
    I was told that russia has his own diamond mines and those were not controled by De Beer the big diamant trader De Beer kept prices high but they had no influence on the Russian market So diamond got valued less in the USSR Therefore they were a bit more genourous with diamond in their tooling. In western countries diamond grinding technologie invested in the binding material more Perhaps that is why diamond got cheaper overe here after the fall of communism in Russia
    I have a few Russian diamond grinding disks and I love them
    Can anyone back up this storry ??

    Peter

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    I used to use light hydraulic oil. I have made the grooves with a hack saw, but not as pretty...lol... Also deeper grooves need more compound. I remember as a kid getting the job of lapping 3 plates for Control Data as they lapped parts on them after they machined them. I had long bars sticking out the ends and it took 2 of us apprentices to left from each side and lowering them straight down. Don't slide one on the other as this can screw it up. Lift straight up and lower straight down. When the stiction gets to much pry up under 1 bar handle with a 2 x 4 board. Your Biceps will get bigger, better eat lots of Wheaties that day for breakfast....lol

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  24. #38
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    Quote Originally Posted by Peter from Holland View Post
    De Beer kept prices high but they had no influence on the Russian market So diamond got valued less in the USSR Therefore they were a bit more genourous with diamond in their tooling. In western countries diamond grinding technologie invested in the binding material more Perhaps that is why diamond got cheaper overe here after the fall of communism in Russia
    I have a few Russian diamond grinding disks and I love them
    Can anyone back up this storry ??

    Peter
    I can't claim certainty, but I'm pretty sure most diamond used in abrasives is man made:

    Synthetic diamond - Wikipedia

    China is one of the big producers, not sure if Russian diamond is crushed natural or synthetic.

    China disrupting world’s diamond sector, tapping sophisticated technology to produce cheap synthetic alternatives | South China Morning Post

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    Quote Originally Posted by Milland View Post
    I can't claim certainty, but I'm pretty sure most diamond used in abrasives is man made:

    Synthetic diamond - Wikipedia

    China is one of the big producers, not sure if Russian diamond is crushed natural or synthetic.

    China disrupting world’s diamond sector, tapping sophisticated technology to produce cheap synthetic alternatives | South China Morning Post

    I am talkinng late 80ies early90ies Not the current situation

    Peter

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    Quote Originally Posted by Peter from Holland View Post
    I am talkinng late 80ies early90ies Not the current situation

    Peter
    Synthetic diamonds for abrasives have been available commercially since the mid-80's. I know that still doesn't answer your question.


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