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fabbing brackets to use hydraulic downfeed from 7x12 saw on 4x6

 

A few years ago I DIY'd a hydraulic down feed for my old (80's?) 4x6 using a cylinder I bought new on ebay.? I was never happy with it.? The cylinder would hold pressure fine, but would let air pass by the shaft seal under vacuum.? So lifting the cutting head quickly would get air in the system.? I used a simple plumbing needle valve (intended for the ice maker on a freezer), which didn't work well for fine adjustment and dropped unpredictably with air bubbles in the system.? After bleeding the air out, it would work ok until I lifted the head to too quickly.? So it was a disappointement.
?
A while back I got a chance to snag a new downfeed control cylinder for a 7x12 saw.? It was free, so got it without checking the resistence direction.? It turns out it free flows when extending and is slow/controlled flow when retracting.? That's the opposite required for a 4x6 when using the traditional mount points.? So when I first mounted it, I could raise the frame very slowly and it would fall freely.? It did the opposite of what I wanted, but it did it very well - so I was happy!

I hacked up a little bracket so I could attach the cylinder above the cutting head hinge point instead of below it.? I haven't looked for 4x6 downfeed kits in years, so I don't know what the current options and prices are.? These cylinders are only $114.? So I thought I'd pass along the details of what I did in case anyone else finds it useful.
?
The bracket is a scrap of 1" box tubing, a scrap of 1/4" plate, a couple pieces of used cutting blade from a lawn vertislicer, and bolts & washers that were laying around.
?
Cylinder and rod clearance took a bit of adjusting after I welded it together, but I have an excuse for that.? The only measuring device used in this project the DRO on the mini-mill to center the holes I drilled.? Other than that,? I'd just hold it in place and put my finger where I want to cut it.? Everything was eyeballed to the "eh, close enough" standard.? There's more than enough shaft travel, so no need for precision.? I clamped the bracket pieces in place on the saw and tacked them, then removed for full welding (you can see by the photos I wasn't paying much attention to the settings onthe welder).? There's just the one bolt holding the bracket on, but the flat piece of vertislicer blade rests in full contact with the pivot arm so the mounting seems stable enough.
?
The bracket sure isn't pretty, but neither is the rest of this old saw.? It looks like its going to work well for me.? The adjustment knob gives me much better control than the needle valve I used on my DIY setup.
?
For free and a few minutes hacking up a bracket, I'm very pleased with it.? In hindsight, I'd probably pay the $114 to buy the cylinder if necessary.
?
 

That's nice fitting. Never seen one above the pivot on LHS. Ingenious - jv


On Wed, 14 May 2025, 10:40 am Joe Blount via , <joe.blount=[email protected]> wrote:
A few years ago I DIY'd a hydraulic down feed for my old (80's?) 4x6 using a cylinder I bought new on ebay.? I was never happy with it.? The cylinder would hold pressure fine, but would let air pass by the shaft seal under vacuum.? So lifting the cutting head quickly would get air in the system.? I used a simple plumbing needle valve (intended for the ice maker on a freezer), which didn't work well for fine adjustment and dropped unpredictably with air bubbles in the system.? After bleeding the air out, it would work ok until I lifted the head to too quickly.? So it was a disappointement.
?
A while back I got a chance to snag a new downfeed control cylinder for a 7x12 saw.? It was free, so got it without checking the resistence direction.? It turns out it free flows when extending and is slow/controlled flow when retracting.? That's the opposite required for a 4x6 when using the traditional mount points.? So when I first mounted it, I could raise the frame very slowly and it would fall freely.? It did the opposite of what I wanted, but it did it very well - so I was happy!

I hacked up a little bracket so I could attach the cylinder above the cutting head hinge point instead of below it.? I haven't looked for 4x6 downfeed kits in years, so I don't know what the current options and prices are.? These cylinders are only $114.? So I thought I'd pass along the details of what I did in case anyone else finds it useful.
?
The bracket is a scrap of 1" box tubing, a scrap of 1/4" plate, a couple pieces of used cutting blade from a lawn vertislicer, and bolts & washers that were laying around.
?
Cylinder and rod clearance took a bit of adjusting after I welded it together, but I have an excuse for that.? The only measuring device used in this project the DRO on the mini-mill to center the holes I drilled.? Other than that,? I'd just hold it in place and put my finger where I want to cut it.? Everything was eyeballed to the "eh, close enough" standard.? There's more than enough shaft travel, so no need for precision.? I clamped the bracket pieces in place on the saw and tacked them, then removed for full welding (you can see by the photos I wasn't paying much attention to the settings onthe welder).? There's just the one bolt holding the bracket on, but the flat piece of vertislicer blade rests in full contact with the pivot arm so the mounting seems stable enough.
?
The bracket sure isn't pretty, but neither is the rest of this old saw.? It looks like its going to work well for me.? The adjustment knob gives me much better control than the needle valve I used on my DIY setup.
?
For free and a few minutes hacking up a bracket, I'm very pleased with it.? In hindsight, I'd probably pay the $114 to buy the cylinder if necessary.
?

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