Supporting > Tooling & Machines

Power Hacksaw refurb

(1/3) > >>

Charles Lamont:
I am afraid setting the scene seems to have needed a rather long introduction.

In 2007 I bought this power hacksaw on Ebay for £75, plus a 3 or 4 hour round trip with a borrowed trailer. It is a Qualters & Smith Sawmaster 150, sometimes labelled 'Terrier'.

It came with a 3-phase motor with a plate that was beyond deciphering. It would need a single phase motor and, not being needed for the projects in hand, it was pushed into a corner and used as a shelf, with a bit of head scratching and tatting about now and then until I made time for a more determined go at it.

In early 2018 I stripped it down. Several parts were cleaned, rubbed down and painted. However, after an hour or two of work with a wire brush in the angle grinder, I decided that if the main body and side cover panels were ever going to be repainted, someone else was going to shot blast them for me first. Although the saw was generally in pretty good condition, with little evidence of ham-fisted use round the vice, for example, the dovetail slide for the saw bow was badly worn and had obviously not seen much lubrication.

I was able to scrounge use of a big Herbert vertical mill to re-machine the dovetail on the main slide casting which sits inside the fabricated arm. The mating slides on the bow are steel bars and these were filed and scraped to fit, removing a considerable amount of curvature.

At this time I bought a new 1450 rpm 1ph motor, and made some adaptor bars to fit it to the existing mounting slots in the base plate. When the saw was reassembled and switched on it was obvious that it was running too fast. The original motor must have been a slower, 6-pole job. The saw got pushed back into its corner while I had a think. I had observed that, at 9-1/2" diameter, the countershaft pulley might fit in the gap bed of the Myford. Hmm.

Now, building a Quorn uses a fair amount of steel bar stock, some of it in diameters that are a bit big for either hand sawing or parting off comfortably, so I decided it is the right time to have another look at the power saw.

Well, it turns out the pulley will fit in the lathe, but only just. In the photo it is just resting on a packing piece. The plan is to turn the big A-section pulley sheave down to take a J-section Poly-V belt, and to make a new steel motor pulley about half the outside diameter of the original alloy one. But there is no way the topside will reach a tool far enough to the left to get at it.

After staring at it a few times, it dawned on me that I could perhaps reduce the secondary driving pulley as well, enough to pass over the cross slide. That would give much better access to the sheave next to the faceplate. It would also contribute to reducing the speed of the saw. However, it would mean reducing the diameter to no more than 4-1/8" OD. Some study of various belting sources indicated that while that was below the minimum recommended diameter for the original B-section wrapped V-belt, a BX-section, cogged, raw-edged belt uses the same groove profile and the minimum pulley is 90mm. I worked out the new lengths and ratios and checked belt availability. Belts are readily available and the resulting speed would be just over 100rpm.

Looks as though it is a goer.             

propforward:
Excellent! I love the detailed intro - slways good to see a hood machine being brought back online - and modified to suit the user. Inventive approach! I will certainly enjoy the progress.

Charles Lamont:
The first, easy, job was to re-drill the motor mounting adaptor pieces again (yes, re-drill again) to suit the smaller width of the new motor pulley.

Next up was drilling the big countershaft pulley for some bolts to fix it to the faceplate. Working at the edge of my shop's capabilities, as is so often the case with this kind of job, I was able to grip just enough of my longest slot-drill's shank to make a spotface so the drill would not wander off down the conical surface.

This setup involved a piece of quite impressive idiocy. I checked I had plenty of Y movement of the saddle to drill the holes on a 6" PCD fore and aft. However, twiddling the handle and counting turns for the front hole I was actually surprised when it stopped part way. The bit of the pulley overhanging the rear of the table had encountered the column. Fool. After completing the hole in the photo I put stops in the front T-slot against the rim either side so that I could use the already drilled hole opposite to line up a 180° rotation of the pulley. If I had thought about it properly, there would have been just enough room to do all the holes in one go by working on the diagonals. Anyway, problem solved. The holes have been tapped and the face cleaned up ready for mounting on the faceplate.

Meanwhile, with the lathe already covered in steel swarf and cutting oil, I decided I would make the motor pulley before cleaning down to a dry machine for a cast-iron session.

Roger B:
A nice tool to rebuild  :)  :)   :wine1:

It looks like you are entering my area or stretching your machines as far as you can  ::)  :ThumbsUp:

Charles Lamont:
Here is the motor, wearing it's newly minted pulley, with the old one and the countershaft pulley, which has some packing pieces glued onto the face so that I can machine it (hopefully) without nurgling the faceplate. The lathe is cleaned down ready, and the new secondary belt is on its way. The primary belt can wait until I can measure things in situ.

Navigation

[0] Message Index

[#] Next page