4x6 Bandsaw accuracy?

[torchroadster]

My wife bought me a Harbor Freight 4x6 band saw for Christmas. Had to send the first one back because it showed up broken, but the replacement arrived this week and I got it assembled last night.

The first test cut shows it to be out of square vertically by about .030 in 4", put a square on the table and checking this against the blade verifies that it is the swing of the blade that is out of square.

Problem is I don't see any good way to adjust it. Googled and found a couple ideas to correct it, but nothing really straightforward or easy - (I really don't want to fab new mounts for the pivot pin or try to mill the table surface).

This is my first bandsaw so I don't really know what to expect for accuracy - but I guess I was hoping for better than this.

Questions:
1. Is this kind of error typical for a band saw?

2. Any good ideas on ways to improve it?

[Bill Pace]

This very popular saw is one of those, quite inexpensive but highly useful, chinese tools that often needs "tinkering" on purchase. And the problem you describe is probably the most common.

If you dont mind this tinkering, and certainly a large portion of us HSM'ers dont, then you will definitely want to go over to the "4x6bandsaw" site on yahoo ----

http://groups.yahoo.com/group/4x6bandsaw/

IIRC, in the files section are descriptions of fixes.

HF made changes in their saws over the last couple years and it seems with the current version -- the "red" one?? -- the adjustable blade guides have gone away .... this was discussed a lot at the 4x6 site, you might wanna read through the back posts or do a search, or ask your question there.

This saw is one of the most used tools in my shop and I'd sure hate to do with out it, --- I think its definitely worth some time getting it set up.

[Carld]

How did you determine that the swing of the band saw is not perpendicular to the table the metal lays on?

[torchroadster]

How did you determine that the swing of the band saw is not perpendicular to the table the metal lays on?

I put a machinist's square on the table and pushed it up against the blade, with the saw full down. I then raised the saw to the top of the square and measured the gap between the square and the blade with feeler guages.

Bill;
Yes, I have a red one. Thanks for the tip on the Yahoo group - I'll check it out.

[Carld]

If the trunions where the band saw pivots at can't be adjusted then the best thing to do is to mathmatically determine the table needs to be machined to get the bore parallel to the table and machine it.

Or you could correctly bore the holes oversize and sleeve them and bore to size.

[Bill Pace]

I may have misread your problem... if it is indeed the trunnions misaligned, this is a much more serious problem. And since the saw is this new, and HF does have a good return policy, then it may be prudent to exchange it..........

I was thinking it was just blade alignment, which , I think, there are some relatively easy fixes.

Here is the method I use to determine my blades alignment, -- of course the little strip of metal can be longer to get different readings. (And, yes, that isnt a HF saw, I got one of the 'swivels' ---- after I wore the HF one out)

[Alistair Hosie]

cant you shim the vice to make it square? It seems a bit drastic I know ,but it may be the only long term solution.I don't have one of these saws as my metal bandsaw is vertical,but I have heard it said here and elsewhere time and time again that immediately on purchase the saw blade should be changed,good luck.Alistair

[Ries]

First, not all of these saws are the same- and the HF one is certainly at the bottom of the barrel. The Jet models are more money, and better made. My two Jet 4x6's both have the word "Jet" cast in 1" tall letters in relief on the bow, so I know that in that way at least, they are different.
They have bearings, not bushings, adjustable blade guides, UL motors, and are generally pretty usable right out of the box.

But none of em, not even the $800 (and that was in 1980 dollars) american made saws these are all based on, will cut very straight over a full vertical 4", and the culprit is the blade.
One of the best things about these saws, from my point of view, is the small, narrow blade. 1/2" by .035, which means that in the upright position, you can freehand cut curves, and the kerf is so narrow that it is quick to cut thru even thick material.
However, the 1/2" x.035 blade is just not stiff enough to cut a clean straight line for 4" vertically. They all wander a bit.
I always cut flat bar in the flat, not vertical position, and find that while the saw is pretty accurate in material up to 1" or so in diameter, its really really rare for one of these to get dead accurate square cuts in 2" square tubing, much less anything bigger.
It will help to buy a good Lennox Diemaster bi-metal blade, at $18 to $22 a shot. They will outlast the cheapo carbon steel blades by months, and cut straighter as well. I run a 10-14 tpi variable tooth for anything under 1" solid, and it works very well, and lasts months in a 3 man shop doing mostly stainless. Order from MSC, or Enco, or Mcmaster.

In other words, you are expecting more accuracy than you are going to get for $150.
You can buy a bandsaw that will cut 4" square dead nuts on every time. American made models start at about $5000. A japanese made Amada will run you $10,000 to $30,000, for full auto.
The blades cost what your saw cost.

You can only gild a turd so much.
Dont get me wrong- I love these little saws, we have two of em in my shop. But they arent miracle workers- they already perform well above their pay grade.

[Fasttrack]

You can only gild a turd so much.
Dont get me wrong- I love these little saws, we have two of em in my shop. But they arent miracle workers- they already perform well above their pay grade.

Yep - i love my HF 4X6 but it doesn't cut perfectly square. I use it like a quieter and, believe it or not, quicker chop saw. Good for rough sawing of large stock or cutting off bits of round bar to stick in the lathe. If i need something to be square i either do it in the vertical mode or i use my lathe/mill to square up the cut end.

I restored a very old wilton model last summer for a relative and i believe the specs on that saw was .008" deviation on 1" or .032" on a 4" span and this was a fairly expensive model with hydraulic down feed and coolant etc.

Of course, that one i adjusted to cut within .001 per 1" but .03 over four inches is acceptable.


You could try returning it for another and see what happens but odds are none of them are going to be perfect. When your actually cutting you will want a new good blade (like Lenox) and lots of tension. You'll notice that the cheap chineese blades will not cut very square at all.

[torchroadster]

Thanks for all the replies -

I understand very well about needing to get a quality blade, and plan to do so, but my concern right now is just the squareness of the blade to the table.

The base of the vise is cast as part of the base so it really can't be shimmed. I could shim the work though and that may be an easy band aid.

I could take it back, but that was why I was asking about how good I should expect or in other words what would be my odds of getting anything better? From the experience of others it sounds like my saw is typical - so I'll probably keep it.

I could fab up new or modify the existing mounts for the pivot pin (trunnion) and that may be a good project for the future. Guess I'll look at it some more tonight and see if I get any other ideas.

[Ries]

I am a little confused, when you say the vise is cast as part of the base.
On my saw, and every one I have seen, both halves of the vise are loose castings, and easy to grind or mill flat if they are out.
The larger half swivels to adjust in one plane, and can easily be machined in the other two.
The moving half of the vise is similar- it is a small, less than 1lb piece that could easily be milled or ground flat.

So it should be no problem to adjust the saw to cut at 90 degrees to the blade, by loosening and swiveling the vise. Call this the x axis. And it should be easy enough to make sure the "fixed" half of the vise is 90 degrees to the table, and to take it off and grind the bottom if its not. This would be Y.

This would take care of the angle in two of three possible planes. The third axis, the "z" axis if you will, is the one most susceptible to blade wander, as the blade drops down thru its arc. And this axis is the one that is toughest to adjust, but, that on the 4 or so Jet saws I have owned in the last 30 years, has always been milled pretty flat from the factory.

Is your saw off on the z axis? If so, the problem is in the trunnions/ bow alignment, as the table is flat, its just not 90 to the vertical movement of the saw. This would suggest inaccurate boring of the holes in the trunnions perhaps, or a similar machining problem.

[kendall]

A few years ago I bought a 4x5 that was much cheaper than the Harbor Fright, had to cut about 400 11" pieces of 1/2 rod on the job, It worked but made the HF seem top line. Had my good one at home, but that was 180 miles south.

I turned a thicker bolt down a bit with and offset 'cam' under the head, threaded it, then bored it to fit the original bolt, re-assembled and used the offset to adjust the cut, snugged the nut on the short bolt to hold it in place any change to the vise angle I adjusted out at the vise.

My good one is a mid 80's buffalo, looks identical to most HF/Grizz etc I've seen, but it's a lot heavier to lug around. Base is still the cheap stampings though.

Ken.

[Your Old Dog]

, but my concern right now is just the squareness of the blade to the table.

The base of the vise is cast as part of the base so it really can't be shimmed. I could shim the work though and that may be an easy band aid.

.

I'm amazed they would make it that way. On my cheap 4x6 both pieces of the vice bolt to the cast iron frame. I can simply swing my vice backer piece and lock it down once its square with the blade. But, even so, I don't think mine would cut 4" with .032 accuracy because the blades are so whimpy. The blade flexes pretty good when it rest on the stock.

[sch]

One aspect is blade tension which should be at least 20 K#/SI, but
better to be in the 24+ range. Achieving this tension is not straight
forward as prior students who have checked this on 4x5 saws found
that good 'hand tight' torquing by those of average strength resulted
in blade tensions in the 12-18 K# range. Others have described small
extenders, such as a piece of wood 10-12" long with a rounded enlarged
section on one end that has two pins sticking out, said pins insert into
gaps in the tension knob and allow a more adequate tensioning.
HSM had an article some time back which correlated blade deflection
in thousandths to a given perpendicular pressure to K#/SI of tension
and described a simple device to measure this. This may be on the
Yahoo site. A google on 4x5 metal band saws will bring up a number
of enthusiast sites in addition to the Yahoo.

[MikeHenry]

I could take it back, but that was why I was asking about how good I should expect or in other words what would be my odds of getting anything better? From the experience of others it sounds like my saw is typical - so I'll probably keep it.

FWIW, the Jet 4x6 bandsaw I bought about 10 years ago cuts square to within 10 thou or better in 4 inches.