Carriage Return Speed w/ Dragback

Rougespear · January 30, 2017, 10:03:03 PM

I'm setting up the speed for my carriage and I'm wondering what people find a good return speed for the head while dragging back a board? Either walk-along or a stationary control station. I have it at about 180fpm and it is so darn fast I think it's scary! Wondering what others find comfortable feet-per-minute wise?

boscojmb · January 31, 2017, 04:28:41 PM

Mine is about 70 feet per minute. I have stationary controls.

I think you could go faster if you are walking with the saw.

Larry · January 31, 2017, 05:24:59 PM

Variable speed only. Anything else is either going to be dangerous or far to slow.

I always return at turtle speed until I catch the board than gradually accelerate up to warp 5. Sometimes I have to return at a slower speed because the board looks like it might shift off the cant. With a slab sometimes they can jack knife if too thin so I can go slow to keep it in one piece.

I sometimes scoot the whole log back to sit better on the bunks or catch a toeboard. I do that pretty slow also.

Rougespear · January 31, 2017, 07:19:22 PM

Larry: a benefit of direct-action hyd levers is their ability to feather flow. I am using a 12VDC electric over hydraulic solenoid so the valve is either wide open or closed. I have flow control in the forward speed, but reverse is wide open. I may just have to play with it some more, but I think I will definitely lower the speed down to about 130fpm instead of 180fpm. Was just curious what others were running speed wise...

Larry · January 31, 2017, 07:32:54 PM

I get variable speed through a flow control valve. Direction control is through a separate valve which is not supposed to be feathered (although it can be). I think there may be a flow restriction in the reverse port because forward and reverse do act differently.

I bet you could plumb forward and reverse through your flow control.

4x4American · January 31, 2017, 08:38:07 PM

I agree, if you can make it variable, do that. As WDH will tell you the WM returns at the speed of light and I can say too, alot of stuff has broken because of that. It must be a way for them to sell more parts :D . I have broken the welds on the dragback 2-3x, last week a board popped over the dragback arm, climbed up, and bent the motor mount for the raise/lower dragback arm, and then yesterday I had a board jab the inside guide roller mount and break the welds on that. All fixable, but, I really wish the pot switch controlled both ways. I wonder if I could do some wiring and make that happen...GaMtnMan?

Bandmill Bandit · January 31, 2017, 09:22:12 PM

WOW! had no idea that the woodmizer return speed could be an issue and I upgraded to the LT40 Super fee drive on mine to get the faster return speed. It was only a few hours till I was use to it and I have not had any issues/breakage at all. I think the return speed is 220FPM but would need Marty to confirm that.

I know I have to be VERY diligent and careful to make sure EVERY thing is properly aligned. proper set up and the return sped are significant factor in daily production.

Higher performance brings higher risk factors and requires a higher level of diligence and awareness on the part of EVERYONE around the mill. Every one needs to keep the performance level of their operations within the parameters of their own abilities.

We all rise to our own level of incompetence. When we reach that point it is time to take a step or 2 back from that and be content with our personal and SAFE best.

On return I use the index finger on my left hand on the top of the return lever so that IF the head should stop for any reason my finger slides off the lever the power is off instantly.

4x4American · January 31, 2017, 10:38:37 PM

Yea thanks Wes, you're a big hero! Don't break your arm patting yourself on your back lol lol lol

barbender · January 31, 2017, 11:05:59 PM

Variable speed on the return would be nice. If I remember right, the power for reverse on our WM's bypasses the H bridge. I don't know what it would take to get it going through there and be able to vary the speed, or if you would need a seperate H-bridge.

Peter Drouin · February 01, 2017, 06:55:14 PM

I would want mine to go faster. But I'm in a chair and can see it all. ;D

Brucer · February 01, 2017, 08:04:24 PM

Quote from: barbender on January 31, 2017, 11:05:59 PM
... If I remember right, the power for reverse on our WM's bypasses the H bridge. ...

You remember right. In the forward position +12 volts is fed to the circuit board that contains the bridge. In the reverse position +12 volts is fed directly to the motor and the cirucit board is isolated.

To get variable speed in both directions, you would have to re-wire your forward-reverse switch so it could reverse the output of the circuit board. That's possible with the existing switch but there would be no way to turn the circuit board off when the switch is in the stop position. You would have to leave the circuit board permanently wired in the "on" position. That would be a really, really bad idea.

One other way to get bi-directional speed control is to replace the innards of the switch. The drum switches are extremely versatile and I suspect you could find a version that is configure properly. What you'd want is one pair of contacts that would be "on" when the switch is in either forward or reverse position. This would be used to send power to the circuit board. The remaining 4 contacts would be configured as a reversing switch to connect the circuit board output to the motor.

Bandmill Bandit · February 01, 2017, 10:02:08 PM

Quote from: 4x4American on January 31, 2017, 10:38:37 PM
Yea thanks Wes, you're a big hero! Don't break your arm patting yourself on your back lol lol lol

Hey 4X4 Sorry came across that way. NOT what I intended at all.

Enhanced performance requires enhanced awareness and diligence for everyone involved AND once you are use to it, that is the new normal. IF the new normal is still uncomfortable, dial it back a bit till it is comfortable. Humanity is still setting and breaking records and I work every day tyo better my last best day. But thats just me!

4x4American · February 01, 2017, 10:02:13 PM

Thanks for the breakdown Brucer. You are much more smarter than I am...I like the drum switch idea, but I don't really have the time to do it. Just to figure out all that wiring would take me a month. I guess that for now I'll just keep on.

I think I might try and redesign my dragback shoe. The chanel iron that I have on there now is part of the problem.

Ga Mtn Man · February 02, 2017, 12:20:50 PM

The standard LT40 doesn't have a MOSFET H-bridge on the FWD/REV control. It uses a Pulse-Width Modulated MOSFET assembly to control the speed and the drum switch is the H-bridge that controls the direction. As Brucer detailed, it is relatively easy to wire these mills to give REV speed control.

Brucer...Why do you say this is a very bad idea? I ran my mill configured this way for a 1.5 years and saw no ill effect. In the end, I decided having to mess with the speed pot for reverse didn't suit the type of sawing that I do. I don't use a drag back.

4x4...Your Super mill does use a MOSFET H-bridge to control the speed AND direction. The drum switch provides low-current control signals to that H-bridge. I took a look at the Super schematic and don't see an obvious way to provide speed control in REV. More info from WM would be required. BTW, your drum switch shouldn't require anywhere near the maintenance as the non-Super mills.

Brucer · February 02, 2017, 05:47:55 PM

Quote from: Ga Mtn Man on February 02, 2017, 12:20:50 PM
Brucer...Why do you say this is a very bad idea? I ran my mill configured this way for a 1.5 years and saw no ill effect. ...

I was referring to the idea of leaving the circuit board powered up all the time, not to the idea of using the speed control in reverse. Don't know if you wired your mill that way or not.

The problem with leaving the circuit board powered up all the time is that it's susceptible to voltage spikes from the various motors in the system. For example, usually we don't try to use our hydraulics when the carriage is moving forward -- on a conventional system the circuit board would not be powered up then.

tawilson · June 24, 2017, 07:24:09 AM

On my mill there are 2 wires above the controller made to connect(male/female connectors) that change the return to variable speed. I just started using the dragback a few days ago so I went variable till I get the hang of it. Glad I did. There's a learning curve. But using the return variable speed takes a little getting used to also.

stihltoomany · June 25, 2017, 02:29:03 PM

I have a 2003 LT40 super. Want variable reverse, don't walk as fast backward as it does. If anyone has a plan for variable speed reverse I am greatly interested. Even if some money for parts was required. WM dealer has not been helpful. Thanks

Magicman · June 25, 2017, 03:23:19 PM

Changing either the drive or driven power feed sprocket or a v-belt pulley might be the best option. That will also slow your forward speed, but you should be able to overcome that with the potentiometer.