Refurbish G8 belt grinder platen

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Rich_Carlstedt
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Re: Refurbish G8 belt grinder platen

Post by Rich_Carlstedt »

You want a hard-flat -long life -surface .
do your Blanchard grind then
Get it Hard Chromed Plated ( Rc 82+ ) ****
or
Gas Nitrated
You will have the best of all worlds

Rich

**** When doing Chrome plating, you get edge effect- this is
where all edges get extra Chrome (Electrons attracted to sharp corners- think Lightening Rods)
This edge has to be re-ground off for flat surface, but "If" you radius the edges first , the effect is not prevalent
Gas Nitride does not do this , but warpage can be a result.
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GlennW
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Re: Refurbish G8 belt grinder platen

Post by GlennW »

Electroless Nickel and baking will get pretty hard without the edge effect if I'm not mistaken.
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Rich_Carlstedt
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Re: Refurbish G8 belt grinder platen

Post by Rich_Carlstedt »

Yes Glenn, good comment and yes - no edge effect with EN, but you need "Hi Phos" Nickel and that will get you Rc78
They do Electroless Nickel in 3 ranges -Low ( <5 %) - Med ( 6-9% ) and Hi (9-13% ) Phosphorus
The Phosphorus makes it very hard and wear resistant
The low is very common and mostly decorative and highly polished and is .0005 to .001" thick ( Flash is .0002")
For wear, you want Hi Phos at .0015" and a "Post Bake" of 600 degree F for 2 hours. ( within 24 hours of plating )
It will not look very shiny at first, but will polish to a mirror with use
Rich
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Harold_V
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Re: Refurbish G8 belt grinder platen

Post by Harold_V »

Interesting thought, chrome plating.
On that same line of thinking, I can think of no good reason why an aluminum platen wouldn't work, assuming it was hard anodized once machined to fit. The only issue I can think of is the coefficient of expansion might be excessive, but the resulting hard surface should last indefinitely.

The Gorton I-22 mills that were in use where I was trained had step pulley drive heads. The pulley included a brake band at the large end, with the pulleys hard anodized. The machines ran 16 hours/day, although there were times when they ran 24. It took years of use to wear through the hard anodized surface for the brake band.

H
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BadDog
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Re: Refurbish G8 belt grinder platen

Post by BadDog »

Wow! Lots of great ideas I would never have considered. Thanks!

I'm not too concerned with lasting another 80 years. I file that under "not my problem". But I would like to be able to get my money's worth of that 5Hp motor when I have big pieces to profile, so it needs to be able to handle both the wear and resulting heat when I lean on it. Flame cut edges on thicker material comes to mind. I've got some 2" thick pieces of CNC flame cut steel that need cleaning at the moment, waiting on this resolution.

The coating ideas likely exceed my budgetary interest, mainly because they all follow Blanchard grinding, and which alone likely answers any needs relevant to my expected life span. Starting with tooling plate comes ground, but adding the coating likely pushes it well past having my existing OEM plate reground.

Starting with some alternate sources seems potentially attractive, depending on relative costs. That valve gate, or clear ceramic look potentially promising, though only preliminary information at best. I could machine my existing platen to take a thinner inset platen (glue?) to suit.

Using a hard anodized aluminum tooling plate could work. I didn't realize hard anodizing was that hard. No idea how price would compare, but I suspect favorable. And how it would deal with that heat (transfer and direct friction) is a question as well. Bolt clearances could handle linear expansion, and that might be enough given aluminums heat transmission properties. But if it heats locally too fast, then I wonder if it would bow. Out of my depth on that one (well, same could be said of most).
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pete
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Re: Refurbish G8 belt grinder platen

Post by pete »

Depending on the material your current platen is made from there's also hard facing using Hardalloy electrode welding. Again it's more than common on surfaces in open pit mining and milling of ore. But with that your again back to at least blanchard grinding for that specific part.
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Harold_V
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Re: Refurbish G8 belt grinder platen

Post by Harold_V »

BadDog wrote: Wed Jul 21, 2021 3:55 pm I didn't realize hard anodizing was that hard.
Think grinding wheel. Hard anodizing is simply a conversion from aluminum to aluminum oxide. The hard anodize process offers the luxury of greater depth, very unlike type 1 and type 2.
how it would deal with that heat (transfer and direct friction) is a question as well.
In my mind, quite well, as aluminum is excellent in regards to heat transfer. Local heating shouldn't be a problem because of its ability to conduct heat rapidly. Hard anodizing is quite slick. I suspect it would have a low coefficient of friction. Sort of contradicts the idea of using it for a brake, but it works quite nicely for that application.

The one limitation is not all aluminum materials respond well to hard anodize. You should have good success with 6061 aluminum, though. I'd start with a T6 or T651 condition if it was my project. Luckily, they are quite common, so they should be easy to procure.

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BadDog
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Re: Refurbish G8 belt grinder platen

Post by BadDog »

Thanks. That may be a viable path.

I've run into another snag getting quotes for the Blanchard grinding. Of the shops I've had recommended for small single item jobs at a reasonable price are all booked out and not even taking new (small) orders. The shortest lead time was 3 months. Of the options that will take it with a few weeks turn around, the cheapest I've found is min estimate of $400, and goes up for time/depth/finish required, to be finalized on price only after job is done. I guess that's why they aren't loaded and booked out 3+ months.

I'm trying to get time to go downtown and talk to a friend this weekend. He thinks he might have a suitable piece of hard plate I can grind on my SG to get smooth/flat. May be AR, which I'm not sure how that will grind. I'll also check on recommendations for AR, and I'm pretty sure he can hook me up with a suitable piece of aluminum fixture/tooling plate for a fair price.
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GlennW
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Re: Refurbish G8 belt grinder platen

Post by GlennW »

Aluminum tooling plate is cast. Fairly soft, and dents easily.
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BadDog
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Re: Refurbish G8 belt grinder platen

Post by BadDog »

I knew it was cast. I may be missing something, but would that be an issue, assuming it's suitable for hard anodize?

Shouldn't be hard to come up with 6061-T6 plate, which I think should be ok as delivered, but problematic should it need ground.
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BadDog
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Re: Refurbish G8 belt grinder platen

Post by BadDog »

I'm also out of my depth here, but wouldn't the tooling plate be comparable to the brake Harold was talking about? I would assume that's also cast, though that may not be a valid assumption, or it may be different alloys/treatment that make it different?
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GlennW
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Re: Refurbish G8 belt grinder platen

Post by GlennW »

BadDog wrote: Thu Jul 22, 2021 3:08 pm I knew it was cast. I may be missing something, but would that be an issue, assuming it's suitable for hard anodize?

Shouldn't be hard to come up with 6061-T6 plate, which I think should be ok as delivered, but problematic should it need ground.
Just seemed odd since you appeared to be concerned about the durability of ground steel tooling plate. Mic 6 dents considerably more easily.

Castings typically don't anodize as well either due to the density.
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