Qualters and Smith (Q&S) 6H power hacksaw refurbishment (hydraulic relief lever, cam and push rod) 

Thanks for your interest and detailed reply. Since posting this video I've fitted a 0.55 kW 8-pole 3-phase motor (680 RPM at 50 Hz) and it seems to work very well. I like the sedate pace this setup gives me as it's only for my personal use. The hydraulics now work fine since making a couple of repairs / modifications but I will bear in mind your suggestions regarding oils. I've not yet cut anything as I'm busy with work. I still need to look for those felt plugs (I've peeped inside and can see the wicks) and will need to add an accessible emergency switch for the VFD. I agree with your suggestion for 24 V controls and already have a couple of PSUs for other similar projects. I would very much like to see a copy of the user manual and parts list but can't post my email address here (some of my students follow this channel and my email address needs to stay private). I will see if I can figure out a disposable email address instead. Once again, thanks for your input.

@@PizzeyTechnology Hi, the felt plugs only become visible if you disconnect and withdraw the reciprocating bow itself, the felt wicks pass through the body of the raising arm and seep oil into the plugs which are recessed in the underside of the lifting arm but hidden by the bow. With the bow removed you can also remove a cover plate in the underside to gain full access to the inside of the reservoir if needed. A good flush with white spirit or paraffin should get rid of the old engine oil without affecting the paint. The oil types and viscosities are substitutes for the original Qualters Smith recommended oils. They are readily available and in smaller quantities than say, an ISO 150 hydraulic oil but compressor oil is just as suitable in terms of its anti foam and wear characteristics in this application. On the slideway, Slideway 68 gives good results without dripping out constantly over time or seeping too slowly to give good lubrication (assuming those wicks and plugs are in good condition). I know what you mean about the motor speed. I think the original speed was intended to make sure cuts on heavier steels wouldn't take too much time in an industrial environment where time = money. It does seem a bit frantic in the home workshop but if nothing else, serves to remind me to keep well clear when it's cutting. By wiring in a non latching roller switch off the main cam pivot (I can see yours still has the cam fitted) you only need push down the main piston lever and step back to get the saw to complete a full automatic cycle of lower - start (as it lowers) - cut - raise and stop. I guess the one you have at school does this. It suits me better because it would be a very unforgiving machine if things go pear shaped with me standing close. On different note, although I replaced all the bushes on mine, the only significant wear I found was on the main double pulley and shaft which sits between the motor and the saw's driving 'flywheel'. Both shaft and bushes are easily replaced. I also fitted some spring oil cups to lubricate all the bushes around the machine. Certainly overkill but dripping a few drops of oil in every now and again makes me feel better if nothing else. Besides, wouldn't be fun without that heady mix of oil, coolant and swarf... I can send pics of my setup along with the user manual if it helps. I do understand the email problem, my daughter is a science teacher.

Thanks for taking the time to provide this valuable information. For reasons unknown your comment was "held for review" and it's only just now that I've had a chance to find and read it in full. I will try disconnecting the bow as you suggested and take a look at those wicks. It will be interesting to see what condition they are in but I'm not too concerned for now as I am keeping it oiled by other means. Incidentally, I used the machine earlier today for a small job and the quality of cut was superb. My impression so far is that wear on this machine is minimal. That "main double pulley" you mentioned appears to be fine and there is no significant knocking elsewhere when the machine is running. Nevertheless, I like the idea of adding some spring oil cups and have previously used them on a small horizontal milling machine -- an AJAX 8" MILLER. I refilled the coolant sump earlier in the week and apart from some muck coming through (as expected) it seemed to work fine albeit somewhat messy as these things can be. However, it wasn't working today so I will have to take another look. I'm not sure whether I want to use it actually, but it's a nice option to have. I would certainly be interested to see those photos of your setup and the user manual.

Following your advice I disconnected the linkage this evening and inspected the felt wipers. They looked to be in good condition, wet with oil, so I left them as they were. Your description of that access panel to the oil chamber was spot on. Keep in touch, Brian

@@PizzeyTechnology Hi, you're very welcome. I'll try to post a brief video of my setup this weekend. BTW eb*y item number 401326303922 is the switch type I used for triggering the stop/start cycle off the cam. I wouldn't trust it at line voltages but at 24v it's perfectly acceptable and means the control wiring can be slender. For the contactor I used a Moeller DIL ER-31-G Panel Mini Contactor Coil 24v LOTEBK96E (because it was small and cheap second hand and easily handles my single phase motor). Almost all the threads on my machine are BSW but I seem to recall that on the vice jaw retainers the larger threads are BSF. You'll notice that In the sliding vice bed there are some pre drilled holes for pegs that go through and set the rear vice jaw to 90 degrees and 45 degrees respectively. The hole sizes are approximately 6mm and 8mm (see the base of the rear vice jaw too). Mine were a little oval so I drilled them out, epoxy glued in some needle bearing inner races of 8mm and 6mm ID and slightly ground down some steel dowel pins to be a snug fit. Makes setting up the jaws a lot quicker when alternating between straight or 45 degreee cuts. The belt driven coolant pump clogs with swarf. I think a mist type (air driven) coolant hose is better or even a simple 3L/5L garden sprayer with a hose off the saw bed into a bucket to reuse the captured fluid. I also put a couple of powerful neodymium magnets on the bed to help catch swarf. Makes for little hedgehogs at the end of a days cutting.

Do you have the same saw?

Yes but mine has a Finn on the top with a counter weight that slides along do u no what size belt to use

Thanks for taking the time to watch the video and provide some useful feedback. I used ISO 68 hydraulic oil to test the system as that's what I had to hand, but please feel free to suggest a better oil if you know of one. Regarding the rate of fall, I have slowed that down since posting the video simply by adjusting the feed-rate lever. I had to play around with the settings as I had to machine a new part (the rod that pushes down onto the valve) as it was damaged. I've also added a "stop" so the rise/fall lever disengages automatically. I presume that function works on your machine. When I get a new motor fitted (hopefully next week) I'll post another video to show it working. Incidentally, if you are using the original Hoover motor (star wired?) did you split the star yourself to use it on 3-phase 220V? Kind regards, Brian

@@PizzeyTechnology I have just rewired my Hoover motor to Delta. It was pretty easy to be fair.

Do you mean there is no lift at the end of cutting, or no lift/relief on every return stroke? If it's the former, then there you may be missing the knock off/stop to put the mechanism into lift mode. However, I'm guessing it is more likely not lifting on every return stroke, in which case I'd start by topping up the oil and checking the adjustment lever.

The saw moves down quite easy using the lever at the right side however, when the cut is complete, it does not return to the up position, its got to be switched off and manually lifted into the locking lever

The rise/fall lever has three possible positions. If you engage the lever up or down, the saw will be in cutting mode, with a slight lift on each return stroke. There is an adjuster if the relief is too great or insufficient. When the saw has completed cutting, the knock off should return the lever to a horizontal position and it will then lift the bow higher on every stroke. Are you missing the knock off? If so, it's easy to make one. Otherwise I'd be looking at topping up the oil and/or adjusting the feed control. My feed control was messed up and I ended up making new parts which proved quite easy. When you get it going it is an excellent saw and makes very light work of cutting. I've uploaded some scans that may be useful. ibb.co/album/vxf8cr

@@PizzeyTechnology I'll have another pop at it next week, many thanks again

There is an adjustment lever to control the feed rate. A heavy oil will also slow it down.

@@PizzeyTechnology I did vary that but I don't think it changed much, maybe I'll see about the oil

It's been a while but I recall needing to dismantle the whole mechanism and making a new rod for the relief valve. I would try topping up the oil first. Good luck.

@@PizzeyTechnology thank you so much, I'll let you know how it goes