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Circular mill saw speed

Started by Osterman.r, May 17, 2021, 06:09:20 PM

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Osterman.r

Hi guys, looking for some input, and hands on seen this/ tried this.
I've been setting up a mill for the past few weeks it's very close to sawing lumber. Yesterday I put the power unit in place and got the mill turning. (Cat d4400)
The motor turns at *DanG near exactly 1,500rpm, 9.5" pulley on the motor, 
27.75" pulley on the mandrel.  
Mandrel turns at 518-525rpm
The saw (52") I have has no bits or shanks and did not come with this mill. My next step is to bring the saw to the saw shop (Groveton nh) and have him put a set of bits and shanks in it and hammer it.
The question is, is my mandrel rpm fast enough, or should I looking into a larger pulley on the power unit? All rpm metering was done with a digital hand held rpm meter that I trust. Also the power unit has 1,500rpm stamped in the name plate. 

Lastly, what is the correct terminology for the shaft that the saw is mounted to? Mandrel? Or arbor? I've heard both.

CCCLLC

Great questions, wish I could help. I'm more familiar with band feeds/speed. Guessing the sawshop will tension  the saw to your rpm.  518+ sounds like a good  speed for that size saw. Looking forward to the input myself.  

grabber green

I think you will be fine getting your blade hammered for your current mandrel speed. Lots of guys used to run slower and lots run faster to. Do You have access to another blade to play with first ? Finding the sweet spot your power unit likes to run (rpm vs peek torgue)  would be helpful if you wanted to spin it faster or slower .   My 0 frick  runs with  52 and 56 inch  blades that both stand up good at 550 rpm.  Also everybody around my area calls it a mandrel but the definition of mandrel vs arbor are mostly interchangable. Good luck.

Jeff

My take has always been the mandrel is the arbor assembly with its fixed collar, where the arbor is the arbor or the shaft. An arbor is not a mandrel until it has the saw collar, its just the arbor. Like I said, my regional take.

That should be a good speed.
Just call me the midget doctor.
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Commercial circle sawmill sawyer in a past life for 25yrs.
Ezekiel 22:30

Ron Wenrich

525 rpm was pretty much the standard on the older mills.  I saw one mill running at 350  rpm, but that was way too slow, and the engine was at an idle.  I couldn't convince the owners they needed to step it up to the 525 rpm.  I've also run mills at 700 rpm.  There is a lot more care needed to the saw at that speed.
Never under estimate the power of stupid people in large groups.

dgdrls

So at 525 rpm a 52" saw will travel at 7141 surface feet per minute.  may be a little slow but as @Ron Wenrich noted that was the speed used on older circle mills

How many teeth/what tooth pattern is your saw? 

Is your Cat a true D4400?  If so, I see it spec's at about 40 H.P.  which is going to be light for power,

It should saw, just not very fast.

Where's @moodnacreek ?? 

D

Dave Shepard

Quote from: Ron Wenrich on May 18, 2021, 09:59:56 AM
525 rpm was pretty much the standard on the older mills.  I saw one mill running at 350  rpm, but that was way too slow, and the engine was at an idle.  I couldn't convince the owners they needed to step it up to the 525 rpm.  I've also run mills at 700 rpm.  There is a lot more care needed to the saw at that speed.
That's interesting. I didn't know saws were run at 700. I played around with a few years ago that had an engine rated at 1,800, but the saw was right at 700, if I remember correctly, and it wobbled pretty bad. Smoothed out around 600, I believe. 
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Osterman.r

Yes it is a d4400. 50hp 420torque 

mike_belben

Doug hasnt posted in a week and im getting a bit concerned about him.
Praise The Lord

Gearbox

Saw tensioning a saw is a art . A good man with a hammer can get a good saw close to the speed you want . A saw that has been hammered on a few times is a crap shoot to get close . When you get it back you will still need to find the speed where it will stand up . Then add enough speed so it will maintain the stand up speed in the cut . 
A bunch of chainsaws a BT6870 processer , TC 5 International track skidder and not near enough time

Osterman.r

I made my first cuts yesterday. It went "okay" if I sawed real slow. If I speed up my feed rate to what I believe is a still quite slow, the saw would start to wobble, and I would get saw dust on the "up cut" or off of the back of the saw. I would either complete the cut, or pull out of it. It would then take a minute or so for the saw to settle down and run true again. My saw guid pins are set to just enough daylight between the pins and the saw when running true. Any thoughts?

Ron Wenrich

When the saw sped drops, does the power unit also drop speed?  If not, then your belts may be too loose.  If it does, then maybe its a governor problem.  One guy told me that belts should be banjo tight.  

When I sawed, I used to listen to the saw speed.  If it dropped in RPM, then I knew that my saw would lay over as the cut was being forced.  You'll heat up a saw, saw off line, or both.  I've watched videos of guys doing this and wondered how their lumber looks.  Not every cut can be made at the same speed since there are many variables that come into play.  Sharpness, species, dryness, amount of knots, etc.  
Never under estimate the power of stupid people in large groups.

moodnacreek

So sawdust was flying at the spreader, that's because you are sawing with the back of the saw, so to say. This is what the lead is all about and why you must have it. But if you are warming the saw it could start to cup and give the same results, same for the teeth not being right or the speed too slow or dropping off. Not enough power. belts slipping, sun on one side of the saw and other things. Welcome to the club.

dgdrls


Speed (HP), heat, bent saw,  arbor issues,
any of those singularly or collectively will cause your issues.



what were you test sawing,  species, size?

D



Ventryjr

I'm Not a expert.  Barley even a novice at this point.  But I was having similar issues with the first few passes on my circle mill.  Rpm on the mandrel ~620rpm. Belts tight. About 250hp at the motor.  Checked lead and track.  Ended up swapping a new set of bits on the saw and it was nothing but wood chips after that.  The old bits looks decent and were finger sharp but I could tell the previous owner had sharpened a few at a angle. 

Also! Be sure to go the correct direction with the speed wrench when removing shanks.  I spent 15 minutes trying the wrong direction.  8)
-2x belsaw m14s and a Lane circle mill.

moodnacreek

On certain days, in certain wood just a few teeth with bad corners will cause trouble. Other times you can saw with a messed up set of teeth. Right now I am sawing locust with a set of teeth that sawed through a bolt that I ground and swedged , no 2 alike and sawing nicely. If the shoe was on the other foot, I would tell you to throw them away.

Osterman.r

Thank you guys, v, I have been following your build closely, we are doing things very similar, although you beet me to the successful cuts. I swapped in new bits right out of the gate. I'm leaning towards v-belt tension, I can turn the engine over with a wrench while holding the mandrel and the engine shieve can spin inside the v- belts. So I think what's happening is as soon I try to feed slightly faster the belts slip and the saw cups and then all of the wildness happens at the saw.

V, post more YouTube videos please. Also, have you found any videos of sawing by the notches? Doug has been explaining it well, but I'd love to see it in action.

mike_belben

On yeah. Thats belt slip.  
Praise The Lord

KenMac

Quote from: mike_belben on June 08, 2021, 06:06:28 PM
On yeah. Thats belt slip.  
Badly worn grooves in the pulley will still allow slippage with a tight belt also. If the belt bottoms out in the groove it won't pull much.
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