Kennedy Hacksaw Dashpot Oil

[Chris VParticipant @chrisv]

I have just acquired a Kennedy Hex60 power hacksaw. It still has the original rubber gaiter over the dashpot. Having read the info on Tony' s Lathes website and the Kennedy brochure online I have bought the appropriate oil and understand the dashpot should be half filled or half an eggcup depending one which source you go by.

Question is how do you put the oil in?

I found I can raise the sawing arm enough that the plunger just comes right out of the pot, so could perhaps use a small funnel to add the oil, but how do other owners do it please?

Chris.

[Chris VParticipant @chrisv]

How much oil and how to fill it?

[john halfpennyParticipant @johnhalfpenny52803]

Pull off the dashpot cover and get the lube in any way you can. The valve should be open, and you will need to be patient whilst the lube passes through the valve to the bottom of the dashpot. Then refit the cover. I use Ford Model A gearbox oil, a 160 weight semi-fluid grease, which just about slumps under it's own weight at 15C.

[Dave HalfordParticipant @davehalford22513]

I just use an oil can to squirt 10-40 oil into the dashpot on my 90. It's not critical, mine is used full off with an industrial blade so it cuts straight but slowly.

How is the bow wear on yours?

[peak4Participant @peak4]

Chris, you will find links to the manual HERE, where on the 4th one there is a recommendation of Wakefield Cresta V
Wakefield is, I think, the forerunner of Castrol.
I think it equates to an old style 500, which is close to a modern 140 monograde gear oil which is what's in mine and seems to function OK.
https://raynerd.co.uk/kennedy-power-hacksaw-manual-and-files/

Bill

[Chris VParticipant @chrisv]

Hmm interesting, thank you John, Dave & Peak4. I got the oil in, I bought SAE 90 GL5 Gear Oil basically following the advice on Lathes website as I know very little about oil. I put a new blade in 24tpi cutting towards the vice fixed jaw/motor. Well actually I tried it the other way first as that's how it came but found basically I think the feed rate was too quick and the saw kept jamming. I was trying this on 25mm x 4mm mild steel, cutting dry. So having turned the blade round to cut on the pull stroke I then cut through 7/8" round brass ok though still with some motor stall, not belt slippage, I checked. Then I put in some 3/4" x 3/4" M/S bar, again it stalled until it had got started properly ie had cut itself a line right across the bar, I them added some cutting fluid which seemed to help.

When it wanted to stall I was constantly relieving the pressure from the cut to keep it going. So this suggests to me I need a thicker oil? Oh yes I discovered the feed speed control works well, so had it turned anticlockwise as far as possible for the steel, ie slow feed, and clockwise for the brass once I'd got started. Maybe Dave you get away with thinner???? oil in yours as you have a more powerful motor I think?

Do you think its my oil choice? Ie I need something thicker??

Also the depth of cut adjuster is a mystery to me, I can adjust the block up and down its bar but that only seems to regulate how far up/down the saw is in the latched upright position, I must be missing something.

Iv'e noticed the Ali base casting is twisted with an old brass shim between it and the top section to even it up so I will want to tackle that but the cut rate is more important right now.

Oh yes it cuts a little out of square but I wasn't expecting it to be perfect, I don't know about the bow wear I'm afraid?

Chris.

[Andy StopfordParticipant @andystopford50521]

I use EP90 in mine and it seems to work OK.

The motor is pretty gutless and will stall quite easily. The feed is supposed to be assisted by a spring pulling the arm downwards – mine has the wrong spring. It is far too powerful and will cause the motor to stall/belt to slip on steel, though it just about manages aluminium, so I have disconnected it. The weight of the arm is good enough for it to work, though at some stage I intend to add a sliding weight, as on bigger power hacksaws.

The blade is supposed to cut on the push stroke, Kennedy were explicit about this in their instructions. I think the idea is that the geometry of the arm and crank is such that it tends to lift the blade on the return stroke. The dashpot then lowers the blade gently back into the cut.

Mine had highly visible wear on the guide arms, and the bearing holes in the connecting rod were badly worn, so it made a lot of noise and tended to be prone to jamming as the bow racked around in the guides.

I bored out the holes in the con-rod and fitted bronze bushes and new pins.

I removed the worn areas on the guide bars with this rather precarious-looking setup:

The retaining bar that runs along the top was badly worn, so I replaced it with a piece of hexagonal brass:

I scraped the bars to ensure that they had a decent bearing area, and adjusted the fit of the brass bar with a couple of beer can shims. The bow was surprisingly free from wear and I left that as is, with just a light scraping to help it bed in with the newly refinished guide bars.

The dashpot boot was perished beyond usability, so I made a mould out of aluminium (couldn't be bothered to try to get the 3d printer to work for this task) and cast a new boot in 2-pack silicone rubber (it feels rather repellent when oily, but it does the job).

The saw works well now – it's not particularly fast, but it's quite accurate, and it gets there in the end. Sometime I'll replace the flat belt drive, which is prone to slipping. Maybe.

[Chris VParticipant @chrisv]

Well 3 hrs later Ive had some good progress. Clearly cutting oil is essential at least on mine, I thought at that speed it would not be necessary….as I write I guess I was getting mixed up with coolant…doh!

The oil is sorted, I just put more in and the problem seems to be solved.

As to the distorted base, I picked a rubber floor mat up of the floor and put the saw on that, I had thought that the saw would jump about but again I was wrong, its a lot more stable and a fair bit quieter now.

I even tried an 18tpi blade for the 3/4" sq steel and it coped fine, I was even able to increase the feed rate once I had it going.

Oh and the spring near the red Bakelite knob needed the tension adjusting so I have adjustable depth of cut now its working right..at least I think it is.

So overall a good Saturday! (-:

Cheers

Chris.

[Chris VParticipant @chrisv]

Thanks Andy, Interesting to hear and see others issues with these!

No certainly not fast, but a darn sight less effort than using a hand saw! I have a vertical wood bandsaw for my brass which works fine but way too fast for steel.

I had obviously missed that about blade direction, I will change it tomorrow.

Chris.

[john halfpennyParticipant @johnhalfpenny52803]

I found EP90 far too thin – the thicker oil gives better damping and feed rate control, but is difficult to get in the small quantity required

[Dave HalfordParticipant @davehalford22513]

Chris,

The direction of cut on the 60 must be dependant on blade. if you cut one in half like Kennedy say, then as the bow only has a pin on the outside and a clamp on the inside to use the other half blade it has to go in with teeth facing the other way.

I only use my spring loaded knob to rest the machine in the up position while putting metal in the vice. There is no height adjustment only a fixed bolt on mine.

I stand mine on some old carpet to shut it up.

I had to file the nose and tail of the retaining bar to dodge the wear ridges on the guide bars. like Andy's mine would stick.

Don't leave it to work on it's own unless you have something to support the piece being cut off. Otherwise it drops down and the saw continues to cut down the length or jams and either the belt or the motor burns.

[Andy StopfordParticipant @andystopford50521]

Posted by Chris V on 01/05/2021 17:41:06:

Thanks Andy, Interesting to hear and see others issues with these!

No certainly not fast, but a darn sight less effort than using a hand saw! I have a vertical wood bandsaw for my brass which works fine but way too fast for steel.

I had obviously missed that about blade direction, I will change it tomorrow.

Chris.

Yes, it might take over an hour to get through a 50mm stainless bar, but then so would I!

Dave, mine has clamps at both ends, no blade holder pin – maybe they added that later – mine is an early one, it has the Hoover motor, and no auto cut-off (something else which would be quite easy to add).

Oh by the way, I use an 18 TPI blade (again a Kennedy recommendation). Definitely desirable for aluminium, 24 might be better for steel, but I generally just use the 18 for everything.

[Dave HalfordParticipant @davehalford22513]

Andy,

Is the switch still there?

[Andy StopfordParticipant @andystopford50521]

Yes, it has the switch, but no evidence that it ever had the rods to flip it

[Chris VParticipant @chrisv]

Thank you Dave & Andy, Ive just had another play with mine.

I noticed the bow was quite loose in the hex guides so played around till I think I found its sweet spot, the hex guides don't appear to be overly worn. It really does not want to cut on the push stroke, I have blade clamps both ends of the bow so can use both ends of a blade.

However on the pull stroke I just cut 2 slices of 1-1/8" round leaded bar, pretty much square and 5 mins per slice, 18tpi blade. Standing there watching it work sure beats doing it by hand so happy enough with that!

I would not leave a machine running unattended as a rule, but isn't that the function of the thermal overload protection and reset button on the motor should it stall?

Mine does have an adjustable 'depth' gauge as per the publicity brochure, but it appears to only control the height the saw is raised for loading & unloading materials, not that this is a great problem.

Its great that it shuts off automatically, but the only advantage of that seems to be if you left it cutting unattended.
If I didn't wish to keep it all original I'd give that function up for a more powerful motor, I wonder why they fitted such a weedy one, cost?

Does anyone have a knob on the end of the right hand facing lifting handle?

Cheers

Chris.

[Andy StopfordParticipant @andystopford50521]

Glad you've got it working well, Chris.

I was using mine this morning, and watching it, the idea that the forward cutting stroke makes the blade lift on the return stroke doesn't seem to hold water – the reverse if anything. I know that I tried the blade both ways, and it worked better forward, but that might have been when the machine was in its original worn state. I shall have to experiment with reversing the blade again.

I remember reading a warning not to leave these unattended because if it jams and the belt slips, the heat generated will ruin the belt, and they are not cheap.

[Matt HarringtonParticipant @mattharrington87221]

I see mto remember somewhere that ISO140 oil was the correct 'stuff'. Anyway that is what I use for the damper and it works well. Mine is converted to v-belt so no flat belt issues like I used to have…

Matt

[Matt HarringtonParticipant @mattharrington87221]

Sorry – I see Bill has already highlighted the oil which I missed for some reason…..

[Peter SaupeParticipant @petersaupe92171]

I set my blade tight in a hand hacksaw with the pins set on there side then clamp the blade into the machine.

[bernard towersParticipant @bernardtowers37738]

Surely what grade of oil you use is a bit of a compromise as the saw will behave differently with 6mm aluminium compared to 50 mm en16!,

[Matt HarringtonParticipant @mattharrington87221]

Bernard, I think that is what the little lever is for (on the damper pot) – to set the rate of fall of the blade depending on the material being cut.

[bernard towersParticipant @bernardtowers37738]

But surely if you are only cutting one piece of material how do you know where to set it . I’ve had mine for nearly 40 years and haven’t adjusted it once and the only time I notice a different sound is when cutting thin material vertically.

[vic neweyParticipant @vicnewey60017]

I have experimented with both oil and springs, it's getting the balance just right.

Another method I tried is to tap a thread in some of the plunger holes and block one or two of them with a grub screw, that works really well in slowing down the pull particularly if you have oil that's too thin. The downside is it lifts more of the oil up into the gaiter when you lift the arm but if it's well fitted with a jubilee clip it's fine.

Here is my saw powering through a one inch bar

My Kennedy

[Ebenezer GoodParticipant @ebenezergood76202]

They are good little saws, I put engine oil in mine, seems to be ok with that. The vice doesn't work well with short stock, I keep meaning to improve it.

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