A new definition of "flat"

wmhammond

wmhammond

Well-Known Member
Hey guys,

I've been on this site for about a year and have been trying to learn to build knives for a little longer than that. About a week ago, on this site in my thread about Hamons John Doyle mentioned to me to put a piece if heat resistant glass over the steel platen on my grinder. Well, I did and I am amazed at how much difference it makes in my grinding. It is unbelievable the difference it makes.

But I am even more amazed that I have been interacting here for a year and have never heard about this before. How many of you guys use glass platens? Does everybody know about this or is it so commonplace that t just never comes up? Boss Dog, you should send a glass platen and a tube of JB Weld to every new member - you couldn't handle all the business. I'm going to post on every introduction a message to get a glass platen :5:. Just kidding but if you don't use one you don't know what you're missing. Thanks, John, for all your help and for this tip.

Wallace
 
I have no idea but you being a nubee like me I'm not surprised you don't use one either. When I looked at my very new platen to prep it for gluing on the piece of glass I did notice a slight ripple horizontally across the platen about midway down its length. Also I notice a lot of difference when I am surfacing a piece of steel lengthwise down the platen before I cut out a knife. My guess is that there are microscopic fluxuations in the way the belt passes over the steel platen as opposed to how it flows over a piece of glass. I'm anxious to see how many "old timers" respond saying they use one and how many don't. Based on my experience, I'm betting most do. Stay tuned.

Wallace

Wallace
 
IMG_3729.jpgIMG_3731.jpgAnthony , the glass or ceramic placed over the platen lets your belt run smoother and much cooler and does not show a wear divot from grinding. As you can see in the pix I added 2 small cap screws on the bottom of the platen , this is in case your JB Weld lets loose it will not ruin your day.
 
The first thing we do in the shop is put on pyroceram glass. We use only JBWeld for a reason. It handles the heat better.
When installing using JBWeld, put the liner level, smear on an even coat of JBWeld, lay on the glass with the least amount of trapped air as possible. Do not clamp it. This sets up stress that will crack the glass later under use. Lightly tape it in place. Watch it for the next twenty minutes as the glass tends to float and move a little until the JBWeld has set up.

it is often called fireplace glass and can usually be purchased locally but you often have to buy a full square foot and pay a cut charge.

The he glass is replaced by heating it with a torch until the epoxy is soft, scraped off and replaced. This is a consume able and the glass will need to be replaced when it wears. It is much cooler due to reduced friction and wears longer than most steel platens. It also nearly always flatter than steel platens.
 
I've been using "glass" on my platens for several years. I actually have a local glass shop that saves its "scrap" pieces of "fireplace glass" for me, and will cut it to the sizes I need. With the cut charge the pieces I buy range from $18-$24. I've used both JB weld and Acraglass to attach the glass to a steel platen..... both seems to work well. The one thing I do, is to build a small "shelf" at the bottom of the platen to support the "glass", just in case the "glue" lets go..... I highly encourage that, because before I did it, I had one "let go"....and can tell you first hand that its no fun at all when a piece of glass gets dragged between a 50 grit belt and the 3" contact wheel on the bottom of my platen! The wife was picking glass shards outta my arms and hands for 3 days afterward! :)

All the points that Tracy makes are dead on! Flatter, cooler, and MUCH longer lasting then any steel platen face.
 
BossDog said:
The first thing we do in the shop is put on pyroceram glass. We use only JBWeld for a reason. It handles the heat better.
When installing using JBWeld, put the liner level, smear on an even coat of JBWeld, lay on the glass with the least amount of trapped air as possible. Do not clamp it. This sets up stress that will crack the glass later under use. Lightly tape it in place. Watch it for the next twenty minutes as the glass tends to float and move a little until the JBWeld has set up.

it is often called fireplace glass and can usually be purchased locally but you often have to buy a full square foot and pay a cut charge.

The he glass is replaced by heating it with a torch until the epoxy is soft, scraped off and replaced. This is a consume able and the glass will need to be replaced when it wears. It is much cooler due to reduced friction and wears longer than most steel platens. It also nearly always flatter than steel platens.
Click to expand...
Do you all have any in Tracy? Last I looked you guys were out. I need to put one on mine. It made a huge difference on my little 1x42 when I put one on it but have yet to on my 2x72.
 
Not quite the glass but I've been using ceramic tile for 8-9 years. The 2'x2' smooth black ceramic tile will last the rest of my natural life cutting 2"x6" liners. It wears well and the cost at the time was about 4 bucks. It also saves a lot of time compared to flattening my platens every couple months. Yes, it does step up your game virtually overnite.



Rudy
 
If you go to Home Depot or Lowe's ,take a straight edge and pick a ceramic tile that is flat, they will cut it for you to size ,no charge and you will get 2 or 3 liners out of 1 tile.
 
I started out with tile and about a year ago I changed to marble with fire glass Acra glassed to it.
 
Good for you Wallace. You're on your way now. :)

I know no one said this, nor is this aimed at anyone but I just want to be clear:

I did not think of this or invent this idea (obviously) and I didn't say that I did or even imply it. I simply mentioned to Wallace that he should try grinding on glass if he isn't already.

That is all. Carry on. :D
 
I recently switched over to glass and Jb Weld. I was using 2" X 1/4" Stainless Steel held in place with 3/8" SS Flat heads as my replaceable platen. I had to replace it every 10 to 15 knives because it would wear a crater at the pressure point. Also where the screws were caused the belt to buckle and mark up my blades with the fine belts. I have only made 4 or 5 knives with the glass platen and I should have done this in the get-go!
 
I do a considerable amount of finish grinding the flats on knives with micron belts. I use a hand held magnet to hold the blade, as i'm sure
many of you do. The problem is that the magnetic force transfers thru the blade and belt to the steel platen and causes all kind of control
problems, especially with small folder blades. Would the use of glass or ceramic tile on the platen prevent this?
 
I had the same problems with magnets before putting a ceramic tile piece on my platen. It immediately fixed the magnetic issue. It's stupid easy to clean up a flat surface.
 
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