Home made disk grinder or a harbor freight sander

JTknives

JTknives

Joined
Jun 11, 2006
Messages
8,650
well i have been thinking a lot about what i need for my knife making today, i think what brought it on was when i was using my homade disk grinder at full speed 3500 rpm when the sanding disk shot off the disk. sienc then i have been thinking is it boing to be better for me to get a cheep belt sander because i have limited funds. i was looking around and found a sander i like which is a 4" by 36" belt and a 6" disk for $89 it has a 3/4hp motor ang i can get it local. its the harborfreight sander,

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93981

When i started making knives i used a standared hand held belt sander fliped over in a vice, i love the wide belts. also i figure that a 36 x 4 = (144 squar inches) belt has the same square inches as a 2 x 72 = (144) so i have the same surface area but in a wider path which makes it eayser for me to for strait edge bevels. let me knon what you think about getting this sander.
 
the 4x36 definitely are a desirable item in a knife making shop. They however, are no substitute for a proper 2x72, home-made or commercial.

Also, the width of the belt doesn't really matter much, when straightness
of bevels is concerned.

In any event, if money's tight, I recommend rolling your own belt grinder.
Look for my posts on how to build one, UPRIGHT style. By far the easiest,
very functional and smallest footprint unit. Alternative design is KMG/Bader-like and has it's merits as well, but is more evolved to make,
has a larger footprint and won't normally give you a buffer in the same unit.
 
well i would love to use my motor in a belt grinder, but the problem is i dont have a shop with all the tools i need to make one. no welder or cutting tourch. what should i do? i was looking and the plans on line for the belt sander that was made out of wood, does it work?
 
JTknives said:
... also i figure that a 36 x 4 = (144 squar inches) belt has the same square inches as a 2 x 72 = (144) so i have the same surface area...
Click to expand...

This isn't the way to look at it. Fact is that you won't be working the middle of that 4-inch belt as much as you might think doing edge grinding. The nice thing about longer belts is that they simply last longer and two inches seems to be about optimum.
A wider belt, or a nice disc grinder, is handy to have as well. There are numerous jobs that lend themselves to more surface area, as I'm sure you know.
I like disc grinders, but the nice thing about a belt is, again, more abrassive area where it counts. (Discs tend to get worked on the edges, so simply adding up inches doesn't give an accurate picture.) They all have their place. I have one (or more) of each.
Rashid11 is right! Get a 2x72. They aren't difficult to make if you understand a few things first.
Above all GET A WELDER!! You won't regret it. (I'd recommend a nice stick welder first. The reason is that it's an easy process that can accomplish quality work on heavy steel with relatively inexpensive equipment. A cheap MIG welder, for instance will probably be less satisfactory than a cheap stick welder. I'd get a nicer, used stick welder. It's the best process for welding the heavier, 'dirtier' steel you'll encounter doing presses and the like, and can do pretty fine work too when you get the hang of it. MIG is good for production on CLEAN steal and TIG is best for small to medium-size work on REALLY CLEAN steal.
 
Speed is the biggest enemy of the new maker. They often buy equipment with 3500 RPM motors. That's just way too fast to use effectively by new makers, and many experienced ones. Buffers running that fast are downright scary.

I won't use anything over 1800 RPM unless it's part of a variable speed setup. My grinder motors are 0-2500 RPM, DC Variables and I rarely even use them to 50% of their speed capability.

There are people who use the high speed motors but they are the exception rather than the rule. Let the abrasive do the job and quit worrying about hogging metal off at light speed. Works just as well and fast at slower speeds and you have more control and treat the metal better.
 
i completley agree with you 3500 rpm is way to fast, i mean if somthing comes off the disk at that speed it will be going 137.8125 feet per secount which is round 100 mile an hr. dont want to get hit with a pice of sanding disk going that fast do we. im realying thinking about getting that harbor freight mutli sander. i know it cheep but i onley have 120 bucks to spend on a grinder and that seemes to have what i need. what i am thinking of doing is getting the 4x36 belts and cutting them into say 2x36 and tracking then to the edge so i can get more use out of the belts. also it kinda small sience i live in a apartment and dont have room for somthing huge. I mean am i making a huge mastake by wanting this sander, i know every one will tell me yes and that i should get a KMG but i bont have that kinda of money. i dont even have to money for a grizzly G1015 Knife Belt Sander. so i think i need to make the best with what i can afford. i like my disk grinder but its just so over powering and i rip disks like every 5 minitues from doing plunge cuts. i just need somthing to get be by while i make some knives i can sell so i can save some money. Im realy thankfull for you help with this question.
 
It sounds to me like you could use a better disc adhesive.

I hope you settle on an arrangement that works for you. Good luck!
 
You must log in or register to reply here.
Back
Top