1x30 sander

V

vaquero57

Joined
Nov 12, 2000
Messages
131
I made a 1x30 sander out of a timing belt tensioner pulley, a serpentine belt idler pulley, an automatic transmission servo piston for the drive pulley on my 1/3 hp bench grinder, and some 2x4s. It works awesome! When I get my digital camera I will let you guys see my shop. This 1x30 hawgs away wood cause it has speed. My question is to you guys; I am not sure I have found a practical use for it other than sharpening. My intentions when I built it was handle shaping but this thing can make handle shaping more difficult. It is hard to shape round handles because it sands flat spots even though it is a slack belt. If you are not careful on a countour it sands down too fast even with a dull220 and will leave a ridge! I am thinking about going back to my old way 4x36 sander then shop rolls using sawing motion and finally sheets. I had better luck this way it seems. Any one care to share how your handle sanding techniques?

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" I am a shootist."
Clay Allison
" Does this mean we are bladists?"
Vaquero57
McAlpin Bladesmithing
 
i use my 2x72 belts to rough out my handles.
On the platen hold your knife blade up and parellel to the belt. I start with a coarse belt. With a light touch start sanding the handle sides use a slight rocking motion to get a slight curve in the side. sand to match your guard or dimension.To do the top and bottom do the same but use a lighter touch and more rocking. This will roughly shape your handle as far a curves go. then its on to the shop rolls using the shoe shine step.I use some of that foam backed sandpaper about 1\8 inch thick glued to a piece of wood trim sanding the long way on a handle to finish. When that sandpaper wears out you can wrap small pieces and keep using it . Takes out the flats.
Hope I managed to get the idea accross.
Take Care
TJ
 
Being new to BF i dont want to step on any toes,&while i agree w/tjsmiths answer,it seems to me, if i understand your question correctly,you need to slow down your belt speed,either by pulleys,or if you are in the coupons,a variable speed dc motor.If it is too fast for handle matl.,it is too fast for sharpening.Like TJ,i use a 2x72 grinder and found long ago that when slack belt grinding on handles,you have to keep the work in motion all the time,stop for 1 second=flat spot.
 
i used my 1x42 slack for handle contouring, i concour about using a light touch and keep it rolling or i cut a series of small 45 degree flats till its almost round then its hand sand time. also its important to kill the edge of the belt with a ceramic stone to keep it from digging in.

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Laurence Segal www.RHINOKNIVES.com
 
I like to use an almost dead belt "used up from cutting steel" of 120 grit cutdown to 1/2"x72" and for a really tight radius I'll go down to 1/4"x72". The narrower the belt the tighter a radius you can turn and the more worn the belt edges are the less they will dig in.

Ted
 
Hey welcome to the forums MIHKNIVES don't worry to much about stepping on toes. We're all here to share our methods and get ideas from how others do things.

I agree about the belt speed, and that the handle has to be in constant motion. The advantage of a belt grinder is that it removes material so fast, but it can sometimes be hard to keep up with it.
If you can, try and figure out the belt speed of your grinder, I'd say that for a fixed speed you want it to be around 2000 sfpm, I think my 4x36 is about 2200 and it does adequately for both handles and blades. Faster will burn alot of materials to easily nad make it harder to control. Slower takes forever on hard stuff.
To figure out the belt speed, take the speed of your motor in RPM's and multiply it by the circumference of the pulley that is driving the belt. If its off of a bench grinder, its more than likely a 3450 rpm motor, so depending on your pulley size that belt might really be moving.

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I may not be the sharpest knife in the drawer... but I've got the sharpest knife in the room.
 
Believe me it is moving. The drive pulley is probably 1 1/4" diameter. Maybe try a bigger pulley?

------------------
" I am a shootist."
Clay Allison
" Does this mean we are bladists?"
Vaquero57
McAlpin Bladesmithing
 
If I understand right you have a pulley attached directly to your bench grinder motor that drives the belt, a tensioner pulley and an idler pulley right?
Its set up kind of like this right?

O - tensioner pulley
I
O- drive pulley------------O idler pulley

If you make the drive pulley bigger, but maintain the same speed with it, the belt will go faster. If you make it smaller and maintain the same rpm it will slow down some. If its only 1 1/4" in diameter, you probably don't want to go any smaller though. You could try and set it up so that you have a small pulley on the motor with a v belt from it to a big pulley thats fixed on the same shaft as your drive pulley. That would slow it down alot depending on the size of your 2 pulleys on the V belt.


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I may not be the sharpest knife in the drawer... but I've got the sharpest knife in the room.
 
Matt , How do you figure? When you increase the circumfrence of a pulley you gear it down. I am trying to remember my automotive classes. I know with the driven pulley or gear the bigger the slower at a given rpm but I believe the drive pulley works on the same prionciple. Look at a 10 speed bike. If you shift the front gear to the smaller sproket If I remember correctly it gets harder to pedal thus being geared up. It has been a long time since I have ridden a bike so I am not completely sure.

------------------
" I am a shootist."
Clay Allison
" Does this mean we are bladists?"
Vaquero57
McAlpin Bladesmithing
 
A 10 speed bike doesn't work on the same principal.
look at it this way, the drive pulley is on a shaft spinning at say 3450 rpm (standard speed for most bench grinders)The belt is moving at the same speed in feet per second as the outside of the pulley.
So, if you have a drive pulley thats 2" in diameter. Its circumference is roughly 2x3.14 or 6.28" Think of it as if the pulley was rolling on the ground,for each turn it would travel the distance of its circumference. So at 3450 rpm it would travel at 21666" per minute, divide that by 12 and you get a speed of 1805.5 feet per minute. Since the belt is moving at the same speed, its traveling at 1805.5 ft per minute.
With a 6" wheel you end up with:
6x3.14=18.84 as the circumference. (18.84x3450)/12 =5416.5 ft per minute. Exactly 3 times faster than a 2" wheel.

If you were to use a small pulley at the drive shaft of the motor, say 2" and a V belt from it to a 6" pulley. The 2" pulley would be turning 3 times faster than the 6" pulley. Having the 6" pulley and the drive pulley fixed on the same shaft so they are turning at the same speed would allow you to slow down the drive pulley without changing the size.

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I may not be the sharpest knife in the drawer... but I've got the sharpest knife in the room.

[This message has been edited by Matt Shade (edited 11-29-2000).]
 
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