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 Post subject: Adamas 32M (550-600 grit) Sintered Lap not cutting well
PostPosted: Thu Mar 31, 2022 12:47 am 
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I bought a 32M (550-600 grit) sintered lap from Adamas Facets/Thomas Smith 4 years ago.

The cutting has slowed a lot 2 different times. The first time I dressed it to get it to cut better by following Tom's instructions. These were to use the coarse 220 aluminum oxide stick (he sold me) at a 45* angle and lightly go back and forth 3 times. It started working again fine.

This last time I did it does not cut well like it did the first time I dressed it. After magnifying it about 40 times there is very little diamond showing. Tom warned not to do it more than 3 times in the instructions or it would start scratching.

I could use some advice from anyone that owns this lap and has successfully dressed it. He said that this lap was different than many other sintered laps.

I watched Justin Prim's Youtube video on dressing sintered laps and I did the same thing as he showed and it still is not showing much diamond. I have a feeling that I need to do more times now until I can see more diamond but want to make sure I don't screw it up. Thanks in advance for any help.

Randy


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 Post subject: Re: Adamas 32M (550-600 grit) Sintered Lap not cutting well
PostPosted: Thu Mar 31, 2022 12:49 pm 
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Not sure what part of So. Ca. your in. More than welcome to bring it by my shop for a look. I disagree with using the stick end as shown in the video, but that's just me. I dress my sintered laps by long edge evenly from edge to center with similar sticks. Agree, to much dressing in one go, ups the chances of embedding loose grit from the stick, but that can be addressed as well if that occurs.

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 Post subject: Re: Adamas 32M (550-600 grit) Sintered Lap not cutting well
PostPosted: Thu Mar 31, 2022 5:10 pm 
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Thanks for the offer to come to your shop. I greatly appreciate it. I am about 80 miles north so would prefer to solve it here if possible but if I can't figure it out I will definitely come and see you. This was my favorite lap.

When you use the long side of the dressing stick is it in line with the lap nut or the other way? How much pressure do you use and do you only do it 3 times total?

When I magnified the lap I can see that the metal that is covering the diamond is kind of bent over (for lack of a better word) and wondered if this is part of the problem.

How do you get rid of stray aluminum oxide bits if there are any? Thanks for your help.

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 Post subject: Re: Adamas 32M (550-600 grit) Sintered Lap not cutting well
PostPosted: Thu Mar 31, 2022 8:16 pm 
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As the AO sticks are normally longer than the width of the lap when purchased I cut mine in half.
As far as more than three times (a very vague instruction), meaning relating to the video you mentioned. I would say yes most definitely, watching that video i am much more aggressive than that appears to be. I think it is being shown as a technic of dressing a lap. I use the long edge for stability and surface evenness.
Clean with lava soap bar scrubbing and run a sacrificial piece of synthetic corundum flat and rectangular on the lap with heavy water, then another piece of quartz or glass and inspecting their surfaces for irregular or stand out scratches. If you see them you can repeat the former cleaning or you can locate the general area if you keep track of placement, use a single edge razor and lightly scrape at an angle. (NOT RUNNING) just rotate the lap by hand.
This is what I do for my sintered laps and they are not Adamas laps so you know, but just as expensive, and what I am comfortable doing is ultimately my lose. So you have to decide what your comfortable with.
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 Post subject: Re: Adamas 32M (550-600 grit) Sintered Lap not cutting well
PostPosted: Thu Mar 31, 2022 9:02 pm 
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Thanks for the quick reply and great advice. I will try it as I have nothing to lose at this point.

Randy

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 Post subject: Re: Adamas 32M (550-600 grit) Sintered Lap not cutting well
PostPosted: Fri Apr 01, 2022 4:26 am 
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On my sintered bronze laps I use the end of the dressing stick, sweeping it back and forth with lots of running water, until the lap cuts the stick aggressively again. You don't need to do this often, so the loss of sintered bronze is negligible. I have never had a grain from the stick embed in the lap; but if you do, you can run the lap dry briefly with a piece of quartz and it will leave a visible comet tail behind the grain, to be removed by scraping with a blade.

After 40 years of use, my oldest sintered lap needed resurfacing because it had developed a shallow annular dishing. This was done on a large rotating cast iron lap with coarse silicon carbide grit (at my local club), until the lap was flat again. Obviously, this removed a bit more material than simple dressing but the lap still has more than 2/3 of its original bronze layer.


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 Post subject: Re: Adamas 32M (550-600 grit) Sintered Lap not cutting well
PostPosted: Fri Apr 01, 2022 1:31 pm 
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I do a similar process to my Batt laps when needing a fresh resurfacing, 100 grit cast iron then a 220, followed by a fine copper brush and through cleaning by running the lap against a lava bar with heavy water.
It's a by hand process, so can be a chore to do and somewhat messy.
And yes never had contamination on the 360 or 600 sintered, but the 1200 is a entirely different beast.

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 Post subject: Re: Adamas 32M (550-600 grit) Sintered Lap not cutting well
PostPosted: Wed Apr 06, 2022 1:31 am 
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I finally had time to try the advice from The Gem Garden and it worked very well. Thanks for all the help from everyone.

Randy


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