Re: Metal cutting bandsaw: Help please
- From: stans4@xxxxxxxxxxx
- Date: 30 Apr 2007 08:28:20 -0700
On Apr 29, 11:36 pm, HC <hboo...@xxxxxxx> wrote:
Hey, all, I have a project coming up that is going to require a lot of
cuts in steel pipe (2 3/8 and 2 7/8 pipe, I'm not sure of the type but
it's not exotic since I'm buying it from a couple of local suppliers
in more-or-less rural Texas; presumably mild-steel). Deciding that
I'd like to have a metal-cutting bandsaw for this work (and for future
use) instead of my chopsaw, I bought a Jet something or another brand
new. The model should be immaterial, but if you need the model number
to answer the questions I can get it for you. Suffice it to say it's
a vertical/horizontal model, automatic shutoff, coolant system, with a
93 inch blade.
It came with a variable pitch blade that I would call a 6/8 by my
measurements but I cannot promise that is accurate. It's close to
that, but I don't know for sure, I'm an amateur at this stuff.
I cut one piece of 2 3/8 pipe with it, super slow, just because I had
to play with my toy. No problems. I then read the instructions
(which is good for me, I usually never read the darned things). And I
read the little Guide To Bandsaws (or similar title) booklet that came
with it in addition to the operator's manual. I bought some Rustlick
50/50 and mixed it according to the instructions I got directly from
the manufacturer (20:1 ratio). I continued cutting the same piece of
2 3/8 pipe as a test only then I had the coolant running. The Guide
said to watch for chip formation and I did and, as the chips were too
small, I advanced the rate of feed slowly until suddenly the saw
started popping and jumping some. After adjusting the rate of feed
some more the thing settled down but didn't cut well. After the cut
was complete I examined the blade and found that tips of numerous
teeth were chipped off. So, after reading the instructions and trying
to adhere to them carefully I had, in fact, ruined a brand new blade
on about the 4th cut. So, I could not expect a bunch of squiggly
chips when the material was not solid/wide enough to produce them it
seemed.
I had purchased a spare blade at the time I bought the saw, but not
knowing the saw came with a variable pitch blade I simply bought a 14
TPI blade. So, I swapped the blades out, convinced that I had
increased the rate of feed on the first blade too much causing the
material to block the blade (the pipe wall is thin enough to fit
between the teeth on the coarser parts). I ran it at a lower rate of
feed and with the coolant and cut a piece of the 2 3/8 pipe, no sweat.
Next, I had a real project to work on so I cut three pieces of metal T-
posts (fencing stuff, supposedly really soft/crappy metal). The first
two cuts went fine, and I didn't think I'd done anything too hastily
or in a bad manner, but the third T-post wouldn't cut more than about
1/8 inch through and then sat there. Skipping some tests and such
what I found was that the 14 TPI blade (that has a, I forget the
technical term, stand-off to the right and left to create a wider kerf
for the back to slide through) was dull on one side and was therefore
only cutting in a diagonal through the material.
So, here I am, I've ruined two blades (a variable pitch 6/8 or
similar, please forgive my lack of technical detail, I'm new at this
stuff, and a 14 TPI fixed-pitch) and I don't know what I've done
wrong. I tried to follow the instructions, to set the feed rate
properly, and even bought the right coolant (a 65 mile trip, each way)
and mixed it according to the manufacturer's instructions. I'm
running the saw a the factory setting which I think is 178 FPM.
Anybody have any suggestions on what I'm doing wrong? Any help is
appreciated.
Thank you.
--HC
A new saw sometimes takes a little tweaking on top of new brand-name
blades to cut straight. You've happened to have picked some of the
toughest stuff to cut with one, too. Teeth being ripped out is a sure
sign of too coarse of a blade pitch combined with too much feed. A
cheap blade will do that, too. Set being worn off on one side
indicates that the guides are probably not set right or the head isn't
coming down perpendicular to the work. A little work with a square
can determine which problem you've got. Were you trying to cut your T
bar with the long leg vertical or flatwise? Should be done flat.
Tubing and pipe will take a fine pitch blade and with hard thinwall
stuff like 4130, you may still have teeth being ripped out if you're
not careful. So get some coarse, medium and fine pitch blades(one
pitch does NOT do it all), Starrett or Lenox brand, tune the thing up
and have at it again. Some of the 4x6 info on the sites out there is
applicable to larger units, too.
Stan
.
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- Metal cutting bandsaw: Help please
- From: HC
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