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-   -   harbor freight bandsaw feed rate (http://www.hotrodders.com/forum/harbor-freight-bandsaw-feed-rate-50632.html)

cboy 10-27-2004 10:26 AM

harbor freight bandsaw feed rate
 
Question for Willys, qctech, or any other owner of a Harbor Freight metal cutting bandsaw. How do you set the torsion on the spring that controls the feed rate of the blade? The directions just say "not too tight", "not too loose". So how do you know what the correct spring pressure is? Maybe if you just gave me the approximate time it takes you to cut a piece of 2X3 rec. tube (cold rolled, .125 wall) or some similar guideline I can go by. I have no idea if I have this thing running at the right pressure.

Dewey

OneMoreTime 10-27-2004 11:22 AM

My Take
 
Dewey

On this it is a bit of an "experiment" if the cut is clean and square you are fine..just start with slow feed rate and then bring it up a bit..if the tool starts to jam or the blade walks out on you then the feed rate needs to be slowed down a bit..

Watch for heating..if the feed rate is too fast the blade will overheat.. Seeing smoke is a good clue..The blade should be cutting not wearing its way through the metal..

Feed rates will vary somewhat depending on the thickness of the metal..When you have made some cuts then you will get the hang of setting a feed rate..

Sam

cboy 10-27-2004 12:18 PM

No smoke, no binding, the blade seem to be running true, and it is not that hot after I finish a cut. So actually I'm a little worried it's "wearing" not "cutting" through the metal. I'm cutting 2x3 rec. tubing, .125 wall, and I'm cutting it diagonally at a 30 degree angle. These cuts are taking an average of about 15 minutes each. Does that sound in the ballpark?

OneMoreTime 10-27-2004 12:25 PM

Seems a bit slow
 
You may wish to try balde that is about 14 teeth per inch..may be the blade you have is a bit too fine..???:) Inspect your balde to see if you have good teeth on it..wearing the metal gives a blade that has no teeth left..I do not think that you have too much concern here..I would not as long as I am getting a good cut..:thumbup:

cboy 10-27-2004 12:39 PM

Thanks OMT.

Beenaway2long 10-28-2004 09:50 AM

As long as the blade isn't getting hot, your OK. Hot blades indicate too fast of a feed or worn teeth. Kind of a quick test that I use, is spray the blade with a lubricant. If it smokes , your too fast or dull. 14 TPI sounds right for .125. Should cut it in about 1 minute or less. The top and bottom may take the most time, but when it hits the sidewalls, it should drop right through.

Also, look at where the blade is welded. Make sure that the weld is ground flush or slightly ground in. If not, it will make the blade catch, skip and start bouncing. This will end up ripping teeth off and trashing a good blade. Not sure of the quaality of a H/F blade, but I use Noton Bi-metals on my bandsaw. Lasts forever.

cboy 10-28-2004 11:34 AM

Whoa, I'm nowhere near one minute. More like 15 minutes. Also, I now have almost NO tension on the spring that controls the rate of the cutting head. I'd actually have to hang some extra weight on the end of the head to get it to apply more pressure at the blade.

Also, I've been checking my more recent cuts and I AM getting some fairly inaccurate cuts. The blade seems to not be dropping at exactly a 90 degree angle to the base of the machine (the vice/bed which holds the stock). As a result, the bottom of the cuts are all about 1/32 to 1/16" shorter than the top of the cut. Since the head is permanently hinged to the base there doesn't appear to be any sort of adjustment for this. Any thoughts?

willys36@aol.com 10-28-2004 11:59 AM

You MUST lube the blade continuously during a cut, especially on the fairly big stuff that you are doing. I keep a squirt can of 30W near my saw and keep the blade dripping the whole cut. Your description of slow cut rate and blade drift are classic signs of a dull blade. Change it, then lube it.

I have always used HF blades and get reasonable run time out of them but nothing like Beenaway is getting with the name brand ones. I guess I'll try a Norton next time to see if it lasts better.

Point is, a sharp blade with the proper tooth pitch that is well lubed should make quick, accurate cuts for a long time.

Haven't really paid much attention to spring tension. I guess I keep it pretty light. As stated by others above, a sharp blade with aggressive enough teeth will virtually eat its way thru the steel and seem to suck itself thru the thin walls of a tube.

OneMoreTime 10-28-2004 01:45 PM

Ok now I;m determined
 
Cboy,
Run the head of the saw to the top of its travel and set your machinsts square against the blade..

Scribe a mark on the bed of the saw where the machinsts square lands..then lower the head of the saw till the blade contacts the bed and place the machists square again against the blade..the blade should come down and hit exactly on the mark..Do this with a new blade in the saw..if the saw is not coming down straight then I dunno..

Now do a trial run on a piece of scrap..bring the tension on the blade up to a point where you have very little deflection when you push on the side of the blade with your finger..

Having to hang a bit of weight on the head of the saw may be needed to put some downforce on the blade..

Mkake yourself a drip bottle using a hdwre store valve..(little needle valve) and a piece of copper tubing arranged so that you can drip lube on the blade..

Now after doing all this and it still does not work..well dunno what to say here..???

cboy 10-28-2004 05:27 PM

I don't think this is a case of "drift" caused by a dull blade. After some more careful inspection, based on OneMoreTime's suggestion, it is clear the blade does not travel at a 90 degree angle to the bed - even when there is nothing being cut. When I put a square on the bed (where the stock is placed) and lift the saw head, I can see that the blade runs out about 1/8th of an inch from the edge of the square at about 5-6 inches above the bed. When the blade is all the way down at the base it touches the edge of the square. As I lift it I can clearly see it running out further and further from the square.

Willys, could you do me a favor and check your saw the same way...lay one edge of a carpenter's square across the bed and the other edge parallel with the blade. Then lift the head up about 6-8 inches. I'm assuming your blade will run true right along the edge of the carpenters square. Since I don't see any way possible that I can adjust how the head (blade) travels in relation to the base, I've got to think there is something amiss with how this particular unit was machined or put together. Let me know if you think there is some adjustment on your saw that I could try to make on mine.

Dewey

willys36@aol.com 10-28-2004 06:33 PM

Maybe you got a bad one. Mine has a run-out of about the thickness of the blade @ 5" above the bed. My experience is that I get very acceptable squareness in my cuts until my blade starts getting dull when it starts to travel severely in one direction.

4 Jaw Chuck 10-28-2004 06:38 PM

Feed rate is determined by the shape of the swarf or "cuttings", you should have nice "curly cues" or figure 9 shaped chips. Tooth pitch is the most important factor when selecting a blade for a bandsaw, you should have three teeth in contact at all times or you risk breaking teeth off, too many teeth in contact raises the pressure needed to effect a cut and also means they will plug up with chips causing increased friction and possibly chip "welding" in the gullet of the tooth.

Here's a good article for reference.

qctech 10-28-2004 08:43 PM

bandsaw
 
Dewey,

I had to play around a bit with my saw but the best thing I did was scrap that hf blade and install a starret from grainger.Works like a charm now. My suggestion to you is check this link out , some real great ideas, hope this helps.
http://groups.yahoo.com/group/4x6ban...yguid=77308368

Anthony

cboy 10-28-2004 08:49 PM

Quote:

Originally posted by willys36@aol.com
Mine has a run-out of about the thickness of the blade @ 5" above the bed.
So at least we know the "run out" in my saw is not common to them all. What you are describing sounds like less than 1/32" in 5" of travel. Mine is more on the order of 1/8" in 4 inches of travel. I just don't think this is a "blade" or "sharpness" issue - particularly when the run out is visible with no workpiece even in the machine.

I just got through emailing H.F. Customer Service to describe the problem. We'll see if they have a solution.

BTW, thanks for the heads up regarding constant lubrication of the blade. Nothing at all in the manual about doing that. I'll have to rig up some sort of drip system.

4 Jaw Chuck 10-29-2004 02:35 AM

You need to set the guide blocks closer to the blade, lightly touching is about right. If yours are rollers the same applies.;)


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