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Sparks up or sparks down?


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I just read a book by Murray Carter in which he says that all his grinders except for a bench grinder the belt/stone turns away from the operator.

 

This seems to make sense to me as I have always had concern about the edge catching.  I grind lathe and woodworking chisels with the wheel coming towards me, primarily so i can see the bevel and the wire edge forming, but I could certainly do this with the wheel/belt running "backwards"

 

So I'm curious if this is a good way to go from the start.

I would welcome any comments!

 

Ben

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some people make them run backwards, because they seem to like the grit and swarf flying into their faces, I prefer the belt dropping the swarf into a bucket I have under the grinding station,  its personal choice.  Why do you think the edge into the belt is a problem ? What are you doing to make the blade catch?  Think about how your lathe would cut if you revered its direction? what is the difference...???

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I'm one of the few who still likes the old 4x36.  I have it turned backwards so it pulls away.  For small knives I can angle it so my eye is looking down the length of the belt, for longer blades I'll lay it flat to take advantage of the larger surface.  As far as grabbing goes, I've had it happen more than once.  From faulty belts to edges that catch to small pieces that slip and get thrown across the shop.  Away is safer.  :wacko:

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I think it depends on where you grind, horizontal on the top the belt should pull away.

vertical on a front plate or on the wheel it should come towards you.

If you can stand in front or at the back of the same machine you dont need to change directions.

I´m not sure if I read the question right because I cant think of any other ways, at least with a belt grinder.

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I have seen at least 1 setup where the flat platten was at about a 45 degree +/- angle with the belt running away from you or backwards. I thought it was a pretty good set up. I have a DC motor I plan to build my grinder with and am hoping to make it reversable so I do have to choose one direction or the other.

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As KRS says...

vertical belt sanding...where you stand at flat platen or wheel as most in the us do the belt goes toward the ground throwing the grit and sparks down.

When you sit and have a large stone wheel that is  (as in most all traditional set-ups) the stone turns away from you. The Japanese stone grinders and those in old Sheffield, ENG worked this way.

It is said the Germans would be on their stomachs with a huge wheel turning below them...also away.

 

I know zero people who use a vertical standard belt sander running toward their face...always down.

 

 

Ric

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From a personal vantage, my set up has the belt turn toward you (downward). If by chance you have a piece get away from you, you can get out of the way if it's going down but you might catch it up side your head if the direction is reversed. Additionally, the debris being deflected downward is better than it coming up under your face shield. Be safe out there.

Peter

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Snip...This seems to make sense to me as I have always had concern about the edge catching.  snip

 

I am puzzled by this concern of yours, it makes no sense to me!   :)

 

If you mean that the thin cutting edge as opposed to the thick back edge of a blade will catch, I would have thought that is more a function of whether the cutting edge is leading or trailing on the belt. I makes no difference whichever direction the belt is travelling as far as I can see.

 

Turn the workpiece over and hold it from the other side so that the thin edge is always trailing perhaps?

 

Alan

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To clarify:  I have always ground edge tools the thin edge up, almost exclusively woodworking tools which typically are hollow ground 1/4 to 3/8  bevel width.  I am comfortable doing this with grindstones.  A knife is much thinner than a chisel and I always sharpen with the edge down but this does not allow me to see the wire edge form without taking it off.  Putting it back on to the wheel it is difficult to get it just right!.  I rarely use holding fixtures, mostly just hand..

 

With the belt direction reversed I would be able to work on the top of the contact wheel and clearly see the edge.  

 

Perhaps i am over thinking because i have not used a vertical flat platen machine.  I just got one and it is obvious that you could not run it backwards without throwing grit and swarf straight up.

 

ben

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I have the edge I am working on, to the top and the top of the belt runs towards me, then down toward the ground.   Have you ever tried it this way or are you just wondering? the question seems odd for a person that has used the equipment, more like a person thinking about getting a grinder type of question.

 

One has to put in a  lot of extra effort to reverse a store bought grinder, as they are all working the downward stroke for knife machines.

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You are correct Steve i have never ground a knife bevel up on a belt grinder.  I am in the process of setting up a shop for knives and have a small Bader grinder, a Wilton square wheel and a Burr King all of which i have used conventionally but never bevel up.  i am not used to how you grind which it seems most people grind.  I am asking so that if it makes sense to run backwards that is what i would like to start out using.  My equipment is three phase so switching rotation is not more than switching two wires and locktite on a couple nuts

 

Thank you to all who have responded!

 

Ben

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  • 1 month later...
  • 1 year later...

If you are using a sharpening belt or wheel, does the top of the belt or wheel rotate toward you and throw the sparks down, or does the top of the belt or wheel rotate rotate away from you and throw the sparks up and away from you? Spark and dust shields (or collectors) can be used with either configuration.

Is one favored over the other, and why?

 

 

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I use mine with the sparks going away from me at the top.  I rarely grind on the wheel.  I use the slack belt behind the wheel.  I can often see the wire edge forming and use that to judge the grind finish across the edge.  

Better visibility, sparks are flying away from me and I can see the trailing edge.

Safer, if I ever lost my grip the blade would be thrown away from me.  

I'm not trying to be ornery, I just want people to realize that there is more than one right way!  I have tried both.

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Not that simple JHCC. if you are using the vertical face of the belt surely you want it down, no doubt.

The question is when you use the top. 

When you sharpen a knife or chisel you want the wheel to turn away from the edge, so using the top of the wheel and having a collector at the back (unless it is a water wheel) would work best. 

 

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7 hours ago, Marc1 said:

Not that simple JHCC. if you are using the vertical face of the belt surely you want it down, no doubt.

The question is when you use the top. 

When you sharpen a knife or chisel you want the wheel to turn away from the edge, so using the top of the wheel and having a collector at the back (unless it is a water wheel) would work best. 

 

Fair enough. I guess the issue is less "up or down" and more "towards or away".

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3 hours ago, KRS said:

Oh boy, do I have to restrain myself to not point you to the search function ^_^

Searching IFI depends on the words or combination of words in the search string. Usually by reviewing the results of the first search you can change or refine the search string and find the information.

The referenced thread was from December 2014 and does discuss the issue. Thank you for the restraint, and the link.

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Normally machines are set so you feed the work into the tool, no matter if it is a saw blade, routers, or grinders.  To those that feel the belt should run so sparks fly up :  Please help me to understand why the manufacturers have the rest on the "wrong" side? and why grinding does not follow the same logic as saws, routers etc with feeding the work into the tool for safety?

I mean the rest is there to hold the work, and should be behind it support the piece right ? So if you reversed the motor in order to get the belt direction running up,  you also need to re locate the knife rest, and drill mounting holes to hold it there. This also means normal 6 inch stone wheel bench grinders also all need rewired and have existing safety guard new rest re-mounted or else you have to remove the safety guard, and press against the support to keep blade from flying up at you, and forget fullers, how can you even see the contact wheel with the newly relocated guard in the way...  assuming you are not already dead from your attempt to polish the fullers having thrown the knife at you rather than at the ground?

My next instalment we will cover the problems installing an anti gravity device to be able to use a water cooling tray,

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Manufacturers look at cutting cost where ever they can, and dummy down the product so the masses do not hurt themselves.

The instructions on a book of matches says to close cover before striking. Almost every instruction manual now says to wear safety glasses, etc etc, and unplug the electric to the appliance before servicing. 

Safety for the masses and weekend warrior can be very different from where you need a comfortable stance, controlled holding power, and can do hours of work at a time. As blacksmiths we safely operate forges, hold hot metal, use power hammers etc on a daily basis. We wear safety glasses because we want to protect our vision, use ear plugs and muffs to protect our hearing, and use other PPE to protect our bodies. We DO NOT grab every piece of metal that we see, we first test and feel for the heat.

Sparks up or sparks down many times depends on the operators first introduction to the machine and the way they were taught to use it. 

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Ha ha, Steve, and you forgot to mention that you can not just reverse the belt, but must undo the belt and turn it around or the joint may fail. 

As far as wheels is concerned, there is no doubt in my mind that a dedicated sharpening wheel must run upwards at the operator side and that the knife or chisel would be placed at one or two o'clock ... so to speak. (Of course if you want to sharpen a knife in the morning then ... :) )

Can you sharpen a knife on a grinding wheel that turns downwards? Sure but it will be awkward if you agree that the abrasive material should run away from the cutting edge since you will have to hold the knife with the edge down and visibility will be scant.

If you are sharpening an axe to split wood, then you may be less particular and a grinding wheel that turns down will do just as well and you can hold the axe with the edge up. The same goes for a belt I think ... I don't have nor need a belt grinder but I imagine I can sharpen an axe on the front of a downward running belt but would most probably refuse to do so with a knife I appreciate. 

 

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