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Power Hacksaw refurb

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Charles Lamont:
The gap end of the lathe bed shears are as-cast and not square across. I had to file a lump off the front of the front shear to get the pulley into the gap, now that it has packers in place.

Clocking up was rather trying and I let it go at a couple of thou TIR, measured on the OD and in the bore. Most jobs I would try for better than that.

Turning down the B-section sheave at the outer end was easy enough, though with a 1-1/8" reduction in diameter, there was quite a lot of metal to be turned into swarf. The new BX section belt has arrived and fits nicely into the groove. I did not know, before starting this job, that pulleys for nominally 40° v-belts are machined at 38°, unless they are smallish in diameter like this one, in which case they are grooved at 34°.

Machining away the A-section sheave next to the faceplate was not so easy, involving juggling tools and toolholders at the extremes of topslide reach. I even considered gaining an 1/8" by taking the felt wiper holder off the front of the saddle, but eventually managed without.

The polly-V grooves were a pain. They ended up not entirely free of chatter marks, even though it was all done in bottom back-gear (nominally 25 rpm) and sometimes with the VFD wound down to minimum, giving just 5 rpm. The pulley is large, the amount of work the saw will have to do small, the belt lightly loaded and slow running, so I do not expect belt trouble even with slightly dodgy grooves. In fact it would probably have been perfectly happy without any grooves in this pulley.   

Charles Lamont:
The secondary belt drive is now all assembled and the belt tensioned. The pulley support bracket ended up in more-or-less the same place as before.

There is plenty of lattitude in the position of the motor. I have placed it where I would like it to end up, measured the centre distance, arrived at a belt length, and ordered one.

I found the bow was loose on its slide, so I adjusted the gib. It now slides pretty smoothly by hand without play. I filled the wick-feed oil reservoir with slideway oil, and replaced the wrist pin.

I was a bit concerned about the next job. The hydraulic drop control worked when I got the saw. As of this morning, not. Some web research gave me an idea how it works. I disconnected the top end and unbolted the lid to have a look inside. Unable to see any oil in it, I was encouraged. A plate on the machine says to use "Century PWLL" for oil points, slide reservoir and hydraulics. Century (and Silkolene and Royal Snowdrift) are now part of Fuchs, with UK headquarters on the old Walkers/Century Oils site in Hanley. I sent them an email enquiry at lunchtime, but unsurprisingly have yet to receive a reply.

Meanwhile I decided to fill it slowly with light hydraulic oil (as used for the Myford spindle). There is what seems to be a level plug half way up the cylinder barrel, but after filling until oil came out of the hole, I had to put a lot more oil in (after replacing the plug) before anything happened. Eventualy the ram met some resistance, with gurgling and slurping as I pulled and pushed the ram up and down. More oil, more resistance. It is now working as it should. It remains to be seen if the return stroke lifting function works when running.

I want to fit a proper contactor/overload and push buttons. These and their boxes are all to hand. I just need to decide where to put them.  I have not decided whether to replace the missing limit switch that stops the saw once it is through the workpiece.       

cvairwerks:
Charles: I would definitely replace the limit switch.

Charles Lamont:
The Poly-V belt for the primary drive arrived today, as well as some crimp terminals. I did not get to it until late afternoon, but I wired the motor temporarily, fitted it, and switched on. It works.

A nice sedate speed of about 85 cutting strokes a minute, rocking slightly on its castors, and once a little grease was applied to the countershaft, by far the loudest sound is from the motor. The back-stroke relief and hydraulic feed is working as it should. I have not tried cutting anything yet.

The next job will be to fit the new switchgear. I did buy a limit switch.

gerritv:
That will be as satisfying to watch as a shaper.

Gerrit

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