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Started by kenfrommaine, July 05, 2016, 10:18:26 PM

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kenfrommaine

Hi
My band wheels are steel 20" x 1.5" how much crown should be put on them? Or is i use bands do they come with a crown?
Thanks
Ken from Maine

boscojmb

I run crowned wheels.

The crown on my wheels in very slight. From eyeballing it, it looks like about .005"

Are you running 1.5" bands or 1.5" band wheels.

I'm running 1.5" bands so my wheels are 1" or less.
John B.

Log-Master LM4

Kbeitz

Grizzly tools sold what they call bands saw tires (that was the rubber cover
that went over the steel wheel) They came with the crown.
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

Satamax

Well, for the wheel crown, there is on the internet; a manual for a recrowning grinder. I can't remember the make, or model. I know i downloaded the instructions. But can't seem to find those. Only thing i remember, is them saying peak of the crown on a normal saw should be placed 1/3 to the front, not right in the middle. It's placed in the middle for a "double cut" cutting forward and backwards.
French CD4 sawmill. Latil TL 73. Self moving hydraulic crane. Iveco daily 4x4 lwb dead as of 06/2020. Replaced by a Brimont TL80 CSA.

Kbeitz

All the bandsaws I ever worked on all had the crown in the middle
and I worked on a lot of them. I even made a wheel or two.
I'm not sure that it would matter .
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

4x4American

Interesting...I'm sure that the crown on our belted bandwheels is centered too
Boy, back in my day..

Kbeitz

Google links say the middle...

https://woodgears.ca/bandsaw/crowned_pulleys.html

But i also found this...

A belt or blade will climb to the largest diameter of a pulley.
If the largest diameter is on the edge of the wheel, that is
were the blade will track. On the large sawmill bandsaws with b
lades a foot wide, the wheels are ground flat.

E-bay has "PRE-CROWNED Bandsaw Tires"

Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

kenfrommaine

Thanks for the replies. The wheels are 1.5" wide x 20". 
Those band saw tires are pricey,  but look like it would do the trick.
Do you think that a crown could be ground or filed onto the wheels if it only has to be a few thousands, I have time and not lots of cash to put into the mill. Maybe make a jig for a belt grinder or such?
Another question with the 1.5" wide wheels I have can I run 1.25" blades or what size would you recomend?
thanks again

york

No,you can not run 1-1/4 in. Bands on wheels that wide-why not bite the bullet and get 19 in. pulleys and be done with it.....
Albert

Kbeitz

I took a flat belt pulley and made a crowned bandsaw wheel out of it
by holding a side grinder to it while the saw was running.
Worked great.

Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

kenfrommaine

 So what width blade would I have to run on those 1.5" wheels? Have a new (supposed) 18hp for power.

Satamax

Quote from: Kbeitz on July 06, 2016, 06:10:10 PM
All the bandsaws I ever worked on all had the crown in the middle
and I worked on a lot of them. I even made a wheel or two.
I'm not sure that it would matter .


Kbeitz, sorry to be picky. But how have you checked? Magnetic base and dial micrometer?  ;D


Quote from: Kbeitz on July 07, 2016, 02:28:22 AM
Google links say the middle...

https://woodgears.ca/bandsaw/crowned_pulleys.html

But i also found this...

A belt or blade will climb to the largest diameter of a pulley.
If the largest diameter is on the edge of the wheel, that is
were the blade will track. On the large sawmill bandsaws with b
lades a foot wide, the wheels are ground flat.

E-bay has "PRE-CROWNED Bandsaw Tires"

http://armstrongblue.com/Band_Saw/BarnhartOperatingInstr.htm

Well, i think there is two things at play. You want the blades to track forward, so the teeth clear the edge of the wheel, and they clear enough so that the tension doesn't change the set.

And the other reason behind the 1/3rd crowning is that when you feed the wood, the blade is pushed slightly backwards.  And the forward crown would  pull the blade back against this movement.

This is all theoretical. I'm no expert.

https://www.youtube.com/watch?v=pvjMwBqDQYA

As well, there's something, over here in France, we use a lot of wide bands. Mine are 4 or 5 inches. And they are slightly "tensioned" so the shape of the band matches the crown of the wheel.





French CD4 sawmill. Latil TL 73. Self moving hydraulic crane. Iveco daily 4x4 lwb dead as of 06/2020. Replaced by a Brimont TL80 CSA.

Kbeitz


Kbeitz, sorry to be picky. But how have you checked? Magnetic base and dial micrometer?  ;D


Checked ???

Checked what... How much crown ?   I just eye balled it to make it look like the other wheel
I had... I have a collection of over 50 flat belt pulleys and each one seems to have a different
amount of crown. So I don't think it really matters.
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

york

Too bad Cooks does not chime in on this,because they re-crown Band wheels.....
Albert

Kbeitz

To really do it right you would need a really big metal lathe.

Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

Czech_Made

Quote from: Kbeitz on July 08, 2016, 07:54:53 AM
To really do it right you would need a really big metal lathe.

Hmm, rotary table maybe?

Kbeitz

Hey... Yea... I got one of those... Never thought of that...



 
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

Satamax

Quote from: Kbeitz on July 08, 2016, 07:54:53 AM
To really do it right you would need a really big metal lathe.
Quote from: Czech_Made on July 08, 2016, 10:32:56 AM
Quote from: Kbeitz on July 08, 2016, 07:54:53 AM
To really do it right you would need a really big metal lathe.

Hmm, rotary table maybe?
Quote from: Kbeitz on July 08, 2016, 11:27:37 AM
Hey... Yea... I got one of those... Never thought of that...



 

Well Kbeitz. Have you ever seen  lathe milling? Throw the dividing table onto the  the chariot after removing the square turret.  And put a big flat mill (bigger than the wheel's rim) in the chuck of the lathe. I even know the trick for turning the crown. Only with flaty mills which have the soldered inserts or screw on inserts which are proud of the base. You use the inside edge of the inserts to machine the wheel. Because the Cutting action of the mill is round, it's tangent at the edge of the rim, and in the center of the rim will be different, because of the shape and size of the flat mill. You most certainly can cut a crown this way. Shim the wheel and dividing table assembly, for the rim to be on center of the chuck, or may be 1/3 off center. As linked above. Tho, to be sure of the end result, a bit of prior thinking, metrology and turning knowlege would be in order

Got it?
French CD4 sawmill. Latil TL 73. Self moving hydraulic crane. Iveco daily 4x4 lwb dead as of 06/2020. Replaced by a Brimont TL80 CSA.

Satamax

A bit like on this one.

https://www.youtube.com/watch?v=foLsg3g7toU

Imagine what would happen if there was a wheel in place of the al block. And what would happen if that wheen was turning.

Far easier with small flat mills, to make the wheel's rim concave, but it can also be made convex.
French CD4 sawmill. Latil TL 73. Self moving hydraulic crane. Iveco daily 4x4 lwb dead as of 06/2020. Replaced by a Brimont TL80 CSA.

Kbeitz

I have a milling attachment for my Southbend lathe.
I dont use it because i have a Bridgeport.



 
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

Satamax

Kbeitz, i don't know those brands. I know the names. That's about it.


You see the advantage of what i was describing. With the rotating table, chuck on top, and the wheel chucked in there, and a flat mill in the chuck of the lathe. Is that you can even remove the tailstock, go at the end of the bed with the cariage; and machine huge wheels without a face lathe. I have a 800mm polish famot from the 60's. Or late 50's. I think i could machine wheels of nearly 2 meters if i realy wanted  ;D Mind you rim width wise, i don't think i could go very far with the chuck on the rotating table. May be 4 inch rim with the wheel directly attached to the rotating table. Mind you, there's simpler ways, a mill with a huge slot table could do as well. The travel on my little rong fu mill is only 370mm or so.
French CD4 sawmill. Latil TL 73. Self moving hydraulic crane. Iveco daily 4x4 lwb dead as of 06/2020. Replaced by a Brimont TL80 CSA.

Kbeitz

Well Southbend was one of our best. The name was sold out to Grizzly Tools.
Bridgeport was also one of our best.

http://www.southbendlathe.com/

https://en.wikipedia.org/wiki/Bridgeport_(machine_tool_brand)
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

Czech_Made

Yeah, milling on lathe is just a substitute for real milling machine.

But every machining job has many different solutions.

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