Can I modify my bandsaw's hydraulic cylinder?

[mjncad]

I'm hoping that KennyD & J_J and any other hydraulics experts will see this thread. It's tractor related since I use my bandsaw for making stuff for my tractor.

I have a Grizzly G9742 bandsaw G9742 4" x 6" Metal-Cutting Bandsaw w/ Swivel Head that I wish had the newer hydraulic down-force cylinder with the ball valve in the line to hold the bow at any position. I have to use the three holes in the base casting to lock the bow in place. This is a nuisance when cutting stock and the bow is a lot higher than the stock. I'm inpatient and tired of waiting for the bow to drop and I have my feed rate where I want it.

I priced out a cylinder with ball valve from Jet for their version of the saw and WMH/Jet wants ~$200 plus shipping. Grizzly wants about $180 including shipping. That's a lot of money for a cylinder and is approaching 1/3 to 1/2 the cost of the saw depending on which brand you buy.

I want to know if I can modify my existing cylinder by adding a small 1/4" FNPT x 1/4" MNPT ball valve that I have on hand. I asked Grizzly tech support and as expected, they advised against it.

My plan is to:
1. Retract the cylinder forcing all fluid to the rod side of the cylinder.
2. Close the feed rate valve.
3. Remove the copper tube.
4. Add the ball valve and use appropriate fittings and copper tubing to complete connection.

The attached picture shows where I want to put the valve.

I'd like to get opinions before I possibly wreck a cylinder and have to spend $200 that I could better use elsewhere.

Thanks!

 

[kenstrac]

What are you trying to do hold the head up while you load yes if not let me know I had a large Johnson that I reworked so it would do what was more efficient for me.

 

[tommu56]

On the jet saw were I at one of my previous jobs I put a solenoid in line so if saw is running it is open and lets it lower and a push button to energize it to lower it manually and the original flow control for speed

tom

 

[J_J]

mjncad,

That must be low pressure hyd to use copper tube. but if it is, sure you could put a ball valve in line to secure the cylinder. Does the band-saw only use the weight of the saw for the pressure? Is that a needle valve in the picture?

 

[kennyd]

Matt,

I have the HDC Version of that bandsaw, I bought it at a "tool show" locally for $200. It has the same cylinder setup that yours does, and I just use the knob to "lock" the bow in place just above the stock when aligning it in the vise. You can't do that with yours? I have not felt a need to change that part of the saw.
I did redo the pivot with oilite bushings to eliminate all the slop in the pivot and it not cuts VERY accurately.

I am just curious what the ball valve will gain you?

 

[tommu56]

Matt,
I am just curious what the ball valve will gain you?

It will lock it in place with out changing the lower speed good for multiple quick cuts.

tom

 

[rockinmywaypa]

I think it should work terrifically for that job purpose. be careful you can't bump it closed or you will struggle to lift the saw until you remember to open it, but it should be super to be able to set the drop rate that you like and leave it alone.

 

[mjncad]

Thank you all for responding so quickly to my questions.

Yes I could just close the needle valve; but I'm lazy and would like to leave the needle valve at a preset feed rate that works for me and let the ball valve act as the brake.

Yes J_J, the weight of the bow is sufficient to push the fluid from one side of the cylinder to the other.

Tom's last post says it more clearly than I did as to what I want to accomplish.

Kenstrac: Yes I want to hold the bow up but closer to the material being cut while I load the stock in the vise and line up my cuts, especially for cuts longer than the built-in stock-stop can handle.

Right now I have to use one of the two non-storage pin holes to hold the bow up while positioning material to be cut. This isn't bad if the stock is high enough that I don't have to wait long for the bow to drop to fine tune the stock for cutting before locking the vise; but is tedious when cutting thin pieces.

 

[kennyd]

Adding a ball valve will be fine-there is no reason not to especially since you already have one. Probably a good idea to change that Chinese hydraulic fluid anyway-I know my gearbox oil was NASTY!

 

[DanD78]

I made my own for a Wells saw I once owned. I took a 6" air cylinder and mounted a Parker PF-B series needle flow control valve between the inlet and the outlet cylinder ports. This valve gives full flow in one direction and an adjustable meetered flow in the other direction. Put a Tee with a plug at the highest end of the cylinder so you can fill with brake fluid.

With this you can use the needle valve to adjust your down speed and you can just raise the saw back up after the cut is done because the fluid will flow unrestricted back through the valve. You don't have to touch the valve between cuts. I don't own the saw any more so I don't have pictures. It worked great for me.

Dan