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homemade circle mill 25"blade gets hot and dishes

Started by buildthisfixthat, September 20, 2010, 08:44:00 PM

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weisyboy

im not talking bout swing mill blades.

we used to run a big mill here until the local council shut us down.

we had breakdown saws up to 90" in diameter. tip speed on all saw benches is 11000fpm.

i have 2 number 3 benches running here 22" blades running tip speed of 11000fpm.

larger the blade the lower the rpm. but tip speed has to stay at about 11000fpm.

all benches run at this speed.

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weisyboy

god bless america god save the queen god defend new zealand and thank christ for Australia
www.weisssawmilling.com.au
http://www.youtube.com/user/weisyboy?feature=mhee
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buildthisfixthat

Quote from: Ron Wenrich on September 21, 2010, 05:37:57 AM
You may want to look into a chainsaw mill for those small logs.  A lot less hassle than trying to invent a sawmill.  I built one for less than $100, not counting the chainsaw.   If you're good at welding, a more substantial one can be made.

What you're doing is probably costing you more than the wood is worth, and it could be dangerous at those RPMs. 
i though about a chain mill but getting enough oil on the chain and keeping it sharp may be a challenge ?how does yours cut do you have any problems
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buildthisfixthat

Quote from: weisyboy on September 22, 2010, 05:02:49 AM
your saw tips should run at 11000 fpm the rpm will depend on the size of the blade.

the saws have to be hammered in just the right way. saws in Australia are no longer hammered but rolled by machinery. the hammering puts a dish in the blade so that when the saw spins up the momentum trows it out straight.

i would recomend you take the rollers off and put packing blocks back in.

the packing should be just firm on the front of the blade and a single block on one side at the back of the blade is a good idea,

watch the blade end on as it spins up it will wobble and once the optimum rpm is reached it will sit streight once that rpm is exceeded it will begin to wobble again.

i would say the reason your blades are heating up is the saw is out of alignment. you should have criss cross saw marks on your timber. can you get us a picture of the sawmarks.

as for tooth hook angel i have no experience cutting pine on benches but in hardwood mill blades, if you put a straight edge along the inside edge of the tooth it should run across the blade at about 1/3 out from the center of the blade.


i will post some picks of the saw cut.why would you remove the roller?after sharpening and flatting the blade it now cuts good but only up to 5"of wood any more and she heats ant takes a left or right turn off the line
shop built bandsaw mill

weisyboy

i just dont like roller guides on bench saws.

we have been using timber wear pads from day dot and they have never let us down. but i have had problem with rollers. scoring the balde and ruining tension.


you should be able to get a 9" cut from a 25" blade but an 7 is more advisable.

how fast are you feeding?


god bless america god save the queen god defend new zealand and thank christ for Australia
www.weisssawmilling.com.au
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Chico

weisboy I think you missed a step in your math somewhere ;D That's a skillsaw chart you're using it's not a very good guide for a headsaw  30 yrs of sawing on big mills and about 750 was as fast as we ever ran a solid tooth and an insert about 550 sometimes 600 You basically have to have a purpose built saw to stand up  the collar has to rt there are a lot of variables guide height, placement of the guide in relation to the saw rim or rings It's the combination of all the rt things that make it run rt You need to string the saw with the carriage you have to make sure the v rail and the mandrell are rt I could go on but you get the pic jmo I also don't want my saw flopping around leaving marks with the back of the saw if it's rt it's sweet if it's not well you know the answer to that
My Daughter My sailor MY HERO God Bless all the men and Women fighting for us today If you see one stop and thank them

Ron Wenrich

Quote from: buildthisfixthat on September 22, 2010, 10:15:35 PM
i though about a chain mill but getting enough oil on the chain and keeping it sharp may be a challenge ?how does yours cut do you have any problems

Keeping a solid tooth blade is way more challenging than a chain saw.  If you need extra oil, you can put on an extra oiler kit if needed.

You already have a carriage that can dog down a log.  I assume you have a way of advancing the log forward on the carriage.  I know you don't have a setworks, but you probably have some sort of gauge to tell you how far to move it to pull a one inch board.

Instead of moving the carriage through the saw, you can move your chainsaw through your log.  Most mills use a horizontal chain saw to do this.  I never had too much luck with that method.  I saw where a guy was using one on the vertical.  It makes a lot more sense, and that's what I did.

I use a Haddon style guide which you can get on Ebay.  I use a 2x6 as a guide.  I support it on the ends and run the saw through the log.  No bending over with the saw, and no backaches.  It produces pretty decent lumber.  I'm just playing around instead of taking the logs to the mill where I work.

The other setup I saw used a metal bar as a guide.  Then, it had a larger metal sleeve that was fastened to your saw bar.  This setup is great if you have a dedicated saw and you plan to saw quite a few logs.  Its a good small log setup and the video I saw, the guy was making cuts in about 30 seconds on an 8' pine log.  The Haddon setup may be able to be converted to this type of setup with some modification.
Never under estimate the power of stupid people in large groups.

buildthisfixthat

Quote from: weisyboy on September 23, 2010, 06:06:02 AM
i just dont like roller guides on bench saws.

we have been using timber wear pads from day dot and they have never let us down. but i have had problem with rollers. scoring the balde and ruining tension.


you should be able to get a 9" cut from a 25" blade but an 7 is more advisable.

how fast are you feeding?the feed is a variable speed gearbox so it depends on what size the cut is .and i m going  with the wood wear pad guides thanks



shop built bandsaw mill

buildthisfixthat

Quote from: buildthisfixthat on September 23, 2010, 09:03:39 PM
Quote from: weisyboy on September 23, 2010, 06:06:02 AM
i just dont like roller guides on bench saws.

we have been using timber wear pads from day dot and they have never let us down. but i have had problem with rollers. scoring the balde and ruining tension.


you should be able to get a 9" cut from a 25" blade but an 7 is more advisable.

how fast are you feeding?the feed is a variable speed gearbox so it depends on what size the cut is .and i m going  with the wood wear pad guides thanks




shop built bandsaw mill

weisyboy

here is a pic of my small resawbench.

16" blade runs at about 3000 rpm.

has only got 2hp 3 phase on it, i am looking for a 10hp petrol to replace it with.



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www.weisssawmilling.com.au
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Tim

Get out the emery cloth and sand paper, builditfixthat.

Make sure that your saw and collars are free of rust. There should be a 3deg. slant to the collars from the rim of the collar to the centre.

Check the set in the saw and make certain that there is some clearance. The wood will heat the saw if it is rubbing the body.

Check your arbour to make certain it is running true.

Also make not of where the saw is heating; rim, collar, whole saw... That will also give you an idea of where the problem is.

Machinery's Handbook 23rd Edition has saw speeds in it. Of course, I can't put my hands on my copy right now but, 1000 RPM for a 25" saw isn't out of line with those tables.
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5quarter

Weisyboy---I gotta say thats a great bench saw. what kind of stuff do you push through there?

Chet
What is this leisure time of which you speak?
Blue Harbor Refinishing

weisyboy

just about anything that needs running down.

stuff under 3" i have done 4 but its underpowered by about 8hp for that.

mainly for re sawing edge cuts down into usable timber.
god bless america god save the queen god defend new zealand and thank christ for Australia
www.weisssawmilling.com.au
http://www.youtube.com/user/weisyboy?feature=mhee
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buildthisfixthat

Quote from: weisyboy on September 25, 2010, 01:51:11 AM
here is a pic of my small resawbench.

16" blade runs at about 3000 rpm.

has only got 2hp 3 phase on it, i am looking for a 10hp petrol to replace it with.




NICE SAW I WOULD GO WITH A KOHLor ENGINE  ..
shop built bandsaw mill

buildthisfixthat

Quote from: Tim on September 25, 2010, 09:05:43 AM
Get out the emery cloth and sand paper, builditfixthat.

Make sure that your saw and collars are free of rust. There should be a 3deg. slant to the collars from the rim of the collar to the centre.

Check the set in the saw and make certain that there is some clearance. The wood will heat the saw if it is rubbing the body.

Check your arbour to make certain it is running true.

Also make not of where the saw is heating; rim, collar, whole saw... That will also give you an idea of where the problem is.
  yes that was the problem the tooth set was to narrow and was rubbing the wood i opened it up to 1/4 kerf now cuts right through blade was cold after cut  im still trying to post some picks of the saw
Machinery's Handbook 23rd Edition has saw speeds in it. Of course, I can't put my hands on my copy right now but, 1000 RPM for a 25" saw isn't out of line with those tables.
shop built bandsaw mill

Chico

In reality a saw collar is measured by thousanths and the taper should only be on the first 3/8 to 1/2 inch or so where is your guides in relation to the eye and the rim of your saw how much lead do you really have in in it and is the tooth spacing and set or swage the same all the way around the saw these are critical factors in saw performance and being free from rust and having flat surfaces where you collars fit is very important  jmo
My Daughter My sailor MY HERO God Bless all the men and Women fighting for us today If you see one stop and thank them

simplicityguy92

so wat is the better rpm 500 or 300 for a circle mill

buildthisfixthat

500 rpms is the better speed most run 500 to 700
shop built bandsaw mill

weisyboy

god bless america god save the queen god defend new zealand and thank christ for Australia
www.weisssawmilling.com.au
http://www.youtube.com/user/weisyboy?feature=mhee
http://www.facebook.com/profile.php?id=100000696669814&sk=photos

Carpenter

Thanks, Buildthisfixthat.  I had a much more detailed explanation but you beat me to it.  It's all a balancing act really between power available, feed speed, and saw diameter.  Weisyboy mentioned rim speed, and I think he has a point however my headsaw 50" is running at 600 rpm and the rim speed is 7850f/m.  It seems to cut pretty well.  Number of teeth play a role in feed speed and power needed as well.  300 rpm would be pretty slow, the blade would not have much inertia to make it through the cut, however I have seen one old blade on a water powered mill that was designed to run slow, so it can be done.  

Ron Wenrich

If rim speed was that important, why don't all mills running a certain sized saw run at the same RPM?  Why is there a difference in shank styles?  Why don't all mills have the same sized collars?  Rim speed is a factor, but not the factor.  I've run 54" blades as slow as 325 or as fast as 700.  They can be made to cut at all those RPMs, and to cut efficiently.  The faster you go, the more the problems.

One factor is power.  Less power means you can drag fewer teeth through the log.  Many guys will only use every other tooth when power is not enough. 

Then there is how the power is delivered.  I've seen guys run big engines, but not enough belts to deliver the power from the engine to the arbor.  That's a problem, but they often know much more than I do and think you can deliver 150 hp through 3 or 4 belts.

Feed speed is important.  I've seen guys take their control stick and pull it back the whole way to feed as fast as they can.  Their lumber looks like it too. 

Sharpness counts, as does proper filing techniques.  You can file lead into or out of a saw.  Sometimes the teeth aren't manufactured very well.  Sometimes the logs grow in a manner that doesn't allow for fast feeding.  When you have problems, you better be able to figure out which ones to target. 

Never under estimate the power of stupid people in large groups.

bandmiller2

Anouther factor with headsaw speed is the chip size per tooth,you want each tooth to take about 1/10 inch per revolution.At high rpm's that log is flying buy you like your standing beside the interstate,anything happens you have little time to react.High speed sucks up horsepower and fuel and throws a big load on your offbearer.As Ron says their are many variables,but when everything works out right you know it. Frank C.
A man armed with common sense is packing a big piece

Tim

Quote from: bandmiller2 on September 28, 2010, 06:56:10 AM
Anouther factor with headsaw speed is the chip size per tooth,you want each tooth to take about 1/10 inch per revolution.At high rpm's that log is flying buy you like your standing beside the interstate,anything happens you have little time to react.High speed sucks up horsepower and fuel and throws a big load on your offbearer.As Ron says their are many variables,but when everything works out right you know it. Frank C.

Actually, the feed rate rule of thumb is 4" per revolution. I built the hydraulic drive on my mill to this capacity. That makes it PDQ, and I rarely, if ever run the feed to this speed. Mind you, I also set up the circuit to return 4x as quick.

I have the headsaw on my sawmill hammered for 800 rpm. Both my 48" and 52" are hammered this way.

I have a Ford 300 6cyl for a power plant on the sawmill with a direct drive through a modified drive shaft. With a good mechanical governor. Quite frankly, it is underpowered. I used what I had...

So: As we've moved away from builditfixthat's issue in the thread... :) I'm sure some of you are looking at this with a raised eyebrow. This is why I set my mill up in this manner:

The blade is hammered for 800 rpm to provide extra stiffness to keep the saw straighter when the rpm drops off in larger stuff, particularly on the first flitches that are taken off.

The feed rate is important. If the rpm drops off the saw tends to wander. Control of that feed rate to a fairly reliable degree contributes to this. The control for my carriage drive is mounted on the floor with a long piece of pipe for a handle to make it easier to feather the valve.

Sharpening is important, both the tooth and the shank. Throw in tooth clearance here as well. Clearing the gullet prevents the saw from scrubbing on the wood. In frozen, or partly frozen wood, it prevents the sawdust from refreezing on the cut and rubbing on the saw. Shanks and teeth have to be centred. 

Rust free saws and collars are important. The slightest bit of dirt in the collar, where it bears on the saw, can cause heating in the saw.

Torque through the drive line will twist the shafts; This twist translates into lost power. Try this with a seized nut and bolt sometime. Put a few extensions between the ratchet and the socket and try to loosen the seized nut, then remove the extensions and do the same. I shortened my drive shaft by 8" and figure I saved about 5% of my horsepower.

There are more issues to running a circular saw than rim speed. Weisyboy's math looks in line to me though...

I've found that if mine is heating, the first place I look is to the sharpening, then cleanliness of the saw.

The 8" saw on the shingle edger I built is running 8000rpm. The 32" blade on my shinglemill is running 1700 rpm. I run the sawmill at 750 rpm... I hate slow equipment, but I feed them to keep the rpm up as well.
Eastern White Cedar Shingles

Jeff

Quote from: Tim on September 28, 2010, 07:39:03 AM
Actually, the feed rate rule of thumb is 4" per revolution.

Actually, that statement can only applied to a given saw with a given amount of teeth.  Bandmiller2's  statement about per tooth is much more accurate.  He said per tooth, per revolution, not just per revolution.
Just call me the midget doctor.
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Commercial circle sawmill sawyer in a past life for 25yrs.
Ezekiel 22:30

Tim

Quote from: Jeff on September 28, 2010, 09:09:57 AM
Quote from: Tim on September 28, 2010, 07:39:03 AM
Actually, the feed rate rule of thumb is 4" per revolution.

Actually, that statement can only applied to a given saw with a given amount of teeth.  Bandmiller2's  statement about per tooth is much more accurate.  He said per tooth, per revolution, not just per revolution.


I should read more closely...
Eastern White Cedar Shingles

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