Fitting an adjustable damper to my power saw

[martin perman 1Participant @martinperman1]

Gentlemen,

I collected my new saw blades this morning and whilst chatting to the saw company owners they asked what damping control my saw had, mine has an adjustable spring, they suggested that the spring method doesn't give a stable even load because as the blade drops down the weight of the carrier frame causes the load to change, its not linear.

They suggested that several customers have modified their saws by fitting adjustable hydraulic dampers, I've had a quick look on the web and haven't seen anything small enough and adjustable, I could make my own but has anybody done this themselves.

Martin P

[martin perman 1Participant @martinperman1]

[larry phelan 1Participant @larryphelan1]

Martin,

This very subject was covered in an article M,E.W a few years back. I still have the issue and will look it up later,if you wish.My intention was to make one for my own saw,but did I? not yet,anyway !

To date I have not had any problems with breaking blades,but there is no doubt that a damper would be a good idea.

This might get me thinking again.

[martin perman 1Participant @martinperman1]

Larry,

It would be very good of you if you could copy it for me please, I've only been collecting MEW for the last couple of years. I will pm my email to you.

Martin P

[larry phelan 1Participant @larryphelan1]

Martin,Have just gone through a pile of my back numbers,without finding it,but do not give up yet ! I have mags all over the place and I did read it,so it,s there somewhere.I will dig up another pile and go through them [better than looking at TV ]

What I need is a better filing system. No,what I need is a filing system !

Hang in there for another while.

[egaParticipant @ega]

Lots of stuff on internet generally eg Yahoo 6×4 group.

The CAHW.exe MEW index would probably help, too. eg MEW 50, page 51

Edited By ega on 22/11/2018 14:22:12

[Brian WoodParticipant @brianwood45127]

Larry,

I maybe have a better filing system than you, all I will need is the issue number when you stumble across it !!

Regards

Brian

[larry phelan 1Participant @larryphelan1]

Martin,

For once the Gods are with me ! Why is it that it,s always the last mag you look at that,s the one you want ?

Went through a pile of them plus many cups of tea and then—-Bingo !

The issue in question is No 126 June 2007.

Now,there are two ways of dealing with this;

A I could try getting photo copies of the pages and post them to you

B I could just post the whole mag to you and you could could send it back when you,re finished with it.

I think this might be the better option since there,s other good stuff in there too.

What do you think?

Larry.

[larry phelan 1Participant @larryphelan1]

Brian,

That would not be hard !

Seems like we both hit pay dirt together !

[martin perman 1Participant @martinperman1]

Larry,

Thank you,

Have PM'd you.

Martin P

[Gary WoodingParticipant @garywooding25363]

See **THIS**

[martin perman 1Participant @martinperman1]

Posted by Gary Wooding on 22/11/2018 15:37:44:

See **THIS**

Gary,

Interesting article, I've tried to join the group but even though I have a login I cant get access to the files.

Martin P

[Clive FosterParticipant @clivefoster55965]

If considering DIY maybe a defunct car or, probably better as being smaller, motorcycle suspension damper might be a good source of most of the components needed. Will obviously need cutting down but taking metal off is easy.

Drilling the rod for a concentric needle valve as per the link from Gary seems a hard way of going about things. In the absence of suitable tube for a concentric design it should be OK to use a separate valve assembly mounted off centre. This appears to be the common way of doing thinks on old school power hacksaws et al. The dashpot on my Rapidor saw is made that way.

Alternatively the valve could be put at the bottom with an external oil return tube. Not seen that arrangement on simple dashpot dampers but I have seen it on rather more sophisticated systems so its known to work.

Clive

(who has about 8 old dampers lying around in the "bound to be useful material" store)

[martin perman 1Participant @martinperman1]

Clive,

You have just clicked a switch in my brain small pneumatic cylinder with both ends connected by a tube with a flow restrictor in the middle, fill cylinder with oil.

Martin P

Edited By martin perman on 22/11/2018 16:13:36

[Brian WoodParticipant @brianwood45127]

Larry,

Thank you, I have the copy in my hand [Smug so and so] I hear you say, what I don't have is a cross referenced index for all these potentially useful ideas that I might want to follow up.

And yes I know we get that in MEW as well for each year.

Regards

Brian

[Clive FosterParticipant @clivefoster55965]

Martin

Glad to be of service. Don't forget that you need a one way valve somewhere so the oil can return freely when the saw bow assembly is lifted ready for the next cut.

Clive.

[Michael Cox 1Participant @michaelcox1]

Posted by martin perman on 22/11/2018 16:03:23:

Posted by Gary Wooding on 22/11/2018 15:37:44:

See **THIS**

Gary,

Interesting article, I've tried to join the group but even though I have a login I cant get access to the files.

Martin P

The hydraulic downfeed and many other improvements to the bandsaw were described in detail, with full constructional drawings, in a series of articles in MEW 227, MEW 228 and MEW 229.

Mike

[martin perman 1Participant @martinperman1]

Mike,

Sadly I didnt start MEW until after those numbers and dont have access to them.

Martin P

[not done it yetParticipant @notdoneityet]

Feb ‘65 ME has the dimensions of the dash pot used on the Edgar T Westbury hacksaw design/build.

[Martin CargillParticipant @martincargill50290]

Pneumatic cylinder idea has a downside in that the two ends of the cylinder don't have the same volumes ( because of the piston rod). I've seen machines using this idea but they have a second cylinder that the fluid uses as a reservoir when the capacity of the rod end of the main cylinder capacity isn't enough. Filling and bleeding the system can be a bugger to do though.

[Dave HalfordParticipant @davehalford22513]

The Kennedy 60 or 90 hacksaw has a very simple open system that works.

[martin perman 1Participant @martinperman1]

Posted by Martin Cargill on 22/11/2018 18:30:08:

Pneumatic cylinder idea has a downside in that the two ends of the cylinder don't have the same volumes ( because of the piston rod). I've seen machines using this idea but they have a second cylinder that the fluid uses as a reservoir when the capacity of the rod end of the main cylinder capacity isn't enough. Filling and bleeding the system can be a bugger to do though.

I think I've got that covered by getting a cylinder that has a little longer than necessary stroke so will never fully empty the restricted end and having filled and bled hydraulic table jacking systems in my last job I think that is sorted as well

[Clive FosterParticipant @clivefoster55965]

Posted by Dave Halford on 22/11/2018 18:35:47:

The Kennedy 60 or 90 hacksaw has a very simple open system that works.

Such open systems, both with and without dust cover arrangements, seem generally to be known as dashpots.

Single acting hydraulic cylinders with the return end open to atmosphere via suitable valve or drilling, so there are no pressure or rod volume effects, are functionally equivalent. I'd be unsurprised to discover that hydraulic cylinder types are commonly used which the more sophisticated variety of flow control valving arrangements.

No real idea where the distinction between dashpot and single acting hydraulics lies. I'd guess that a dashpot system is one that can be filled from a jug or squirt can whilst a hydraulic cylinder may need more sophisticated arrangements. Both arrangements are obviously self bleeding so no special efforts are needed to extract air entrained during the filling process. However a single ended hydraulic system may require a few operating cycles to clear any air that may have got in.

Clive.

[I.M. OUTAHEREParticipant @i-m-outahere]

I used a pneumatic ram on mine with a small header can to allow for the difference in cylinder volume due to the piston rod . I eventually switched over to a larger header can with the pick up pipe submerged in hydraulic oil , it is just a re purposed fuel tank off a briggs horizontal engine mounted below the vise locking handle – its not pretty but it works well , i made a metering block that also serves as a pivot point for the ram .

[martin perman 1Participant @martinperman1]

Larry Phelan,

I have pm'd you.

Martin P

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