Metal cutting bandsaw: Help please

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
Reply to
HC
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I don't claim to be an expert, but I have two horizontal saws. One is a 7X12 Wilton that I run with a 4 TPI blade and coolant. NOTHING less than 1 inch wide goes into it. I've yet to wear out a blade. The other is a little HF 4X6. I run a 16 TPI Sterrett blade in it, dry, and use it mostly for cutting tubing. I never really counted, but I get several dozen cuts out of a blade.
The key is to use a blade that is fine enough to have 3 or (better) 4 teeth in contact with the metal at all times. And, when cutting steel, slower is generally better...
On most horizontal bandsaws, it is the pressure, not the rate of feed, that is adjustable. It is a good idea to be very slow and gentle when starting the cut and then increase the pressure as the cut gets well established. Otherwise you may knock teeth off on the sharp corner.
Jerry
Reply to
Jerry Foster
Hey, Jerry, thank you for your reply and time.
When you say that "nothing less than 1 inch wide goes into it" do you mean solid stock, not tubing or I-beam or angle, etc.?
I think I totally failed on the number of teeth in contact with the material with the variable blade. :(
If I am recalling correctly that this thing runs about 178 or so FPM, is that too fast for steel? The material is chilly (not cool, actually chilly) to the touch after the cut, so I don't think I'm encountering too much friction.
On mine it retards the rate of fall. That then means that if the material resists it the weight (pressure) will increase, I think.
Thank you again.
--HC
Reply to
HC
Sounds like the fencepost had a hard spot- they're overall pretty soft but no guarantees. If you torchcut something like that and then saw close to the first cut you're likely to find some hard spots.
John
Reply to
JohnM
That popping and jumping was the tips of the blades being torn off.
Been there..done that..really sucks when its your last blade.....
Discovering your downfeed cylinder decided to blow its seals......
Gunner
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Reply to
Gunner
One tip was already give: At least 3 teeth have to be cutting. Thinwalled tube/material -> finer blade.
Second, look at the guide of the blade. If it is pressing on the side of the teeth, adjust it.
And, you need to break in new blades. Manufacturer says, 100mm^2 with slow speed and feed through some *solid* bar. When they are a bit dull, you don't risk ripping off teeth when cutting thin material.
Nick
Reply to
Nick Mueller
Are these blades the ones that come with the saw? Most of those are junk. Buying a good quality blade will make the machine seem like another saw.
Reply to
Gary Brady
You pushed the first blade too hard, it caught and ripped the teeth out. Get a good quality, bimetal, fine tooth blade from Starret and you should be good to go. On pipe, you should expect to see small filings, not big chips. Wall thickness is about .150", you want 3 teeth in contact so 14 or 16 tpi is the coarsest tooth you could use.
The fence posts were likely high carbon, they will rip up a blace quite quickly. They were the second worst thing you could have cut (absolute worst is rebar- use the chop saw on that!)
HC wrote:
Reply to
RoyJ
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
Reply to
stans4
Stick with the chopsaw for the fence posts. I wouldn't cut any more scale than I had to either. To me that would be like taking tiny cuts with HSS tooling on a rough iron casting.
I have had the 4 X 6 HF style saw for at least 20 years.. My 64 1/2" X .025 blades cost about $25 each (Doall Imperial 100). If you are paying proportionally a lot less, you are getting poor quality blades. Don't waste your time with them. My default blade is 14tpi. Even when cutting sheet metal, I have never lost a tooth and I cut solids up to 4" diameter with the same blade successfully. I'm not saying that I'd do it the same way if I had a production shop, but it takes about 12 minutes to cut 4" round of mild steel with that blade. I don't have coolant capability, but I drizzle a little cutting fluid on the blade sometimes when cutting (annealed) tool steel.
Pete Stanaitis ------------------------------------
Reply to
spaco
... with a bandsaw
Guiding a length of pipe into/through a bandsaw is a difficult task. And bevel cuts with a floppy bandsaw blade are near impossible.
Have you considered a plumber's pipe lathe instead (for square pipe cuts, that is)?
Reply to
whit3rd
Um, have *you* ever looked at a horizontal bandsaw?
GWE
Reply to
Grant Erwin
Are you talking about splitting a piece of pipe?
And what's so hard about mitering pipe? Floppy blade? Not on mine.
Steve
Reply to
Steve B
That number can't be right. It must be something in the 500..1000mm^2 range.
Nick
Reply to
Nick Mueller
Jerry, I'm sorry for the delay in responding. Thank you for your time and answer. I certainly did not have 3 or more teeth in the work. In reading some more of the responses to my post I get the feeling, in general, that the bandsawing method is a very slow method of cutting metal (I'm not complaining, just stating what my feelings are). Is that accurate to say? How can I tell if I'm going too fast (besides the destroyed blade)?
Thank you again for your time.
--HC
Reply to
HC

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