TSB

screen printing => Equipment => Topic started by: Prosperi-Tees on October 06, 2014, 05:59:42 PM

Title: Mac Valve Replacement
Post by: Prosperi-Tees on October 06, 2014, 05:59:42 PM
Does the whole block of valves need to come out to replace one?
Title: Re: Mac Valve Replacement
Post by: sqslabs on October 06, 2014, 06:22:30 PM
Depends how far into the block the one you have to replace is.  But for the most part, yes.  The valves are held together on rods, so to get to one on the inside, you have to remove all the valves outside of it.  Keep an eye on the seals during the process, and make sure they stay in place or you'll have to do the whole process all over again.  And again.  And again.   
Title: Re: Mac Valve Replacement
Post by: Prosperi-Tees on October 06, 2014, 06:30:15 PM
Im replacing #1 so I should be able to just take out the one to the right of it then. Wish me luck, I didn't want to pay $160 to have it replaced so hopefully this goes smoothly.
Title: Re: Mac Valve Replacement
Post by: sqslabs on October 06, 2014, 06:47:01 PM
It's really not as hard as it seems once you see how it all goes together. The seals are the only tricky part at times. Good luck man!
Title: Re: Mac Valve Replacement
Post by: Binkspot on October 06, 2014, 06:53:46 PM
If not too much trouble pull the whole assembly and stand it up on end, let gravity work for you. You do not want the rest to start sliding around and the seals leaking. To hold the seals a little grease or vasiline.
Title: Re: Mac Valve Replacement
Post by: Prosperi-Tees on October 06, 2014, 06:59:24 PM
My luck, the little allen screws holding them... I dont have that size in the shop lol. Oh well I will get to it tomorrow. Kind of a slow week so trying to get all this done.
Title: Re: Mac Valve Replacement
Post by: jsheridan on October 06, 2014, 07:01:43 PM
You only have to replace the bad one.

The little pins screw into each other and hold the entire block together.

Just be sure to put the seal that goes between them back in it's channel or you'll have leak issues.

Title: Re: Mac Valve Replacement
Post by: JBLUE on October 06, 2014, 10:16:50 PM
Why are you replacing the whole valve? You should just have to replace the spool on those and they will work as good as new.
Title: Re: Mac Valve Replacement
Post by: CGS on October 06, 2014, 10:51:03 PM
Those screws that hold the bank together are metric 3 mm. 
Title: Re: Mac Valve Replacement
Post by: Prosperi-Tees on October 06, 2014, 11:42:00 PM
Why are you replacing the whole valve? You should just have to replace the spool on those and they will work as good as new.
Ok school me on the spool?
Title: Re: Mac Valve Replacement
Post by: Admiral on October 07, 2014, 12:00:43 AM
On our challenger III I believe we have issues with the mac valves.

Are the screens / squeegees not coming down right away due to bad mac valves?  Sometimes we will have to keep hitting the print button / reset on the head to get the screen to finally drop then it works fine for the run...

Only an issue on a couple heads but it would be nice to fix it.
Title: Re: Mac Valve Replacement
Post by: Gilligan on October 07, 2014, 12:21:33 AM
Admiral, how old is this press?
Title: Re: Mac Valve Replacement
Post by: 244 on October 07, 2014, 07:03:29 AM
On our challenger III I believe we have issues with the mac valves.

Are the screens / squeegees not coming down right away due to bad mac valves?  Sometimes we will have to keep hitting the print button / reset on the head to get the screen to finally drop then it works fine for the run...

Only an issue on a couple heads but it would be nice to fix it.
A Challanger III does not have Mac valves. The valves are SMC valves. The valves if sticking may of been exposed to air with burnt oil from a compressor. Solution is to change valve on head but find reason for burned oil first. Probably worn compressor seals.
Title: Re: Mac Valve Replacement
Post by: Binkspot on October 07, 2014, 08:00:30 AM
Change the whole thing, you paid for the complete valve use it. It's like buying oil and a filter for you car but only changing the oil. Can you just change the spool, is it easier, sure. More then likely the spool and body are worn or scored, you may not be able to see it, it works on tight tolerances. You could go through all this trouble, just change the spool and still have the problem, worse yet you could damage the spool in the old body and have to buy another valve assembly.

Keep everything clean when working on the valve body, make sure no dirt or lint gets in there.
Title: Re: Mac Valve Replacement
Post by: Prosperi-Tees on October 07, 2014, 10:23:26 AM
Thanks Brian, SQS and John for your help, much appreciated, I will let you know how it goes.
Title: Re: Mac Valve Replacement
Post by: Admiral on October 07, 2014, 01:54:14 PM
On our challenger III I believe we have issues with the mac valves.

Are the screens / squeegees not coming down right away due to bad mac valves?  Sometimes we will have to keep hitting the print button / reset on the head to get the screen to finally drop then it works fine for the run...

Only an issue on a couple heads but it would be nice to fix it.
A Challanger III does not have Mac valves. The valves are SMC valves. The valves if sticking may of been exposed to air with burnt oil from a compressor. Solution is to change valve on head but find reason for burned oil first. Probably worn compressor seals.

Thanks Rich, will pursue this.

This was an issue with the previous owner.  We are still working on getting the auto as close to 100% as possible.
Title: Re: Mac Valve Replacement
Post by: 244 on October 07, 2014, 03:17:02 PM
On our challenger III I believe we have issues with the mac valves.

Are the screens / squeegees not coming down right away due to bad mac valves?  Sometimes we will have to keep hitting the print button / reset on the head to get the screen to finally drop then it works fine for the run...

Only an issue on a couple heads but it would be nice to fix it.
A Challanger III does not have Mac valves. The valves are SMC valves. The valves if sticking may of been exposed to air with burnt oil from a compressor. Solution is to change valve on head but find reason for burned oil first. Probably worn compressor seals.

Thanks Rich, will pursue this.

This was an issue with the previous owner.  We are still working on getting the auto as close to 100% as possible.
I understand. Buy a couple of the valves on the rear of the heads. They are sticking due to burnt oil in a over worked or worn compressor. The effect is called coking. The burnt oil turns to a tar like substance and the poppet stick in the valve. When its working its fine but when the valve sits non functional for a while the tar prevents the poppet from causing action in the valve. Only solution, replace valve.
Title: Re: Mac Valve Replacement
Post by: Gilligan on October 07, 2014, 03:36:42 PM
You getting it Gerry?
Title: Re: Mac Valve Replacement
Post by: Prosperi-Tees on October 07, 2014, 05:37:12 PM
You getting it Gerry?
unfortunately no, I forgot my tools this morning and had to get some paying work done today.