Adjustable Tension Pivots/Slides

Here's a neat way to obtain adjustable tension on a pivot or a slide in a simple mechanism -- install a washer 'sandwich' made of two flat washers and a split lock washer, like so.

 A self-locking nut, e.g. a ny-lock nut or a prevailing- torque nut, is essential to the assembly. Pictured is an output chute from a snow thrower. With its original complement of fasteners and washers, the chute couldn't be tensioned and tightened properly -- it wouldn't stay set at a desired angle. I've fitted the chute with washer sandwiches, and now it should operate as it's supposed to. Thankfully, a working trial on a snow-covered driveway is a ways off.

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A Wheelbarrow Restoration

My next door neighbour has a decrepit old wheelbarrow languishing down by her shed. It's in rough shape.

She's graciously let me have the wheelbarrow for a restoration project. Here's a view of it upright at my place.

The wooden parts will have to be remade -- they're beyond salvage. The tub and the other steel parts are in reasonably good condition. The tire is a write-off; I know that because I've tried to repair it before, and it's a cracked ruin that will never hold air again. I happen to have a complete replacement wheel/tire on hand, so that's taken care of.

The first order of business will be to dismantle the thing, so I can get the dimensions of the one complete handle/rail for recreating a pair. That's liable to be a bit fraught -- the fasteners are probably all seized.

I'll start with the front cross-brace.

And the axle/wheel assembly.

Once I get the axle/wheel off, I'll go no further until I've done a trial fit of the new wheel.

Here's the front cross-brace off and reasonably well straightened out.

I'll need new carriage bolts. They're 5/16" x 2 1/4".

I got lucky with the axle fasteners -- they weren't seized.

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And here's a view of the new wheel/tire in place.

When I add the setscrews to the collars, I'll be able to lock the wheel in place axially on its axle. That will make for a stable, trouble-free wheel installation.

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Progress -- MONDAY, MAY 4, 2015

Here's the wheelbarrow with new wooden parts, and all new fasteners.

Now it needs to have its handles formed, and everything painted.

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All Done -- MONDAY, JUNE 1, 2015

And there we are -- looking much better than in the first photo.

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Update -- TUESDAY, MAY 7, 2019

The weather is finally turning springlike, so I went to look in on the wheelbarrow. Its tire was completely deflated. I reinflated it. The next day, the tire was again deflated. So there's an end to it -- I'm not going to muck about with an unreliable wheelbarrow wheel. I went and bought a flat-free replacement, like so.

Is that sharp or what?

Of course, this wheel replacement couldn't be easy. Where would be the fun in that? There are a couple of snags.

Snag No. 1

The old wheel has a 3/4" bore, so the axle is like so.

The axle is 3/4" diameter in the middle where the wheel bears on it; 5/8" diameter at its ends where it's held by the axle brackets.

I could go either of two ways to resolve that issue:

1. I could go get a three foot length of 5/8" diameter rod from the Home Depot.
2. I could turn down the axle to 5/8" diameter overall in my lathe.

Option '1' is tempting, but option '2' is cheaper, and way more challenging, so I'll give option '2' a try.

Snag No. 2

The new wheel's hub is too wide to fit between the wheelbarrow's axle brackets. I'll have to cut down the axle brackets' noses to enable the new wheel to fit.

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So here's the commencement of Snag No. 1's resolution.

I've centre-drilled one end of the axle to take a live centre.

And here's the axle chucked and centred, about to be turned down to 5/8" diameter.

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And Now I Remember How The Axle Was Made

It's not 3/4" diameter rod turned down to 5/8" at the ends like I'd been thinking; it's 16mm diameter rod turned down to 5/8" at the ends, and bushed up to 3/4" diameter at its centre with a length of steel tubing and epoxy. The rod was salvaged from a scrapped plotter back when I worked as a printer technician. I had to turn down its ends just a bit so that 5/8" collars would fit it. Here's a view of it with the bushing material completely stripped away.

And as for Snag No. 2, I solved that nicely by filing two of the oblong mounting holes in the axle brackets with a 5/16" round file.

So I didn't have to cut down the brackets' noses as I'd been thinking.

And here's the wheel installed.

Aside from a periodic oiling of the wheel's steel sleeve bearings, I now have a maintenance-free wheelbarrow.

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Roadside Find -- An Executive 56 Swimming Pool Pump

Well, what have we here?

It's an Executive 56 four horsepower pump for use with swimming pools, spas and hot tubs -- quite a piece of gear. It appears to be seized. Further investigation is in order.

At the face-end of the pump, there's a mystery small-diameter tube/fitting, and eight screws.

Let's see what's inside.

The screws are 8-32 x 5/8" stainless steel. The pump's end has to be knocked off forcefully -- there's a big ring-seal around it that makes it a snug fit in its recess.

The impeller scarcely budges when I try to turn it. The main body of the pump will have to come off, and it appears that the only way to remove it is to take out the four long through-screws from the motor. Here goes.

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And it turns out that that's not how it's done. The impeller is supposed to unscrew from the motor's shaft. Good luck with that.^[1] From what I can see, these pumps are not a serviceable item. That's why the whole thing was replaced, when the motor is probably still perfectly good.

I'll keep the stainless steel screws and the line cord; the rest can go to the scrap yard.

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Update -- SUNDAY, APRIL 19, 2015

My son advised me to remove the pump, so the motor could go to the scrap yard 'clean' -- i.e. in its most valuable state, without a lot of worthless plastic attached to it.

A judiciously applied pry bar, and my impact wrench, got the impeller off in pieces. Here's a view of the motor's output shaft.

It's in rough shape, and the bearing is noisy.

What happened here is that the pump's seal leaked, and water corroded the shaft and attacked the bearing. All of these units probably fail that way eventually.

Even if the output end of the motor were still ok, the motor wouldn't be of much use as a utility motor. That 1/2" diameter stub-shaft is not up to the task of transmitting four horsepower to a pulley, and then to something like a table saw or a compressor. Also, the motor is not reversible.

These motors are purpose-built to power a pump, and that's all they're good for. Once they fail like this one did, all they are is scrap metal. It's an awful waste, but that's the modern way of things.

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Note:

[1] The 'dry' end of the motor's shaft is accessible by way of an easily removed plug button. That shaft-end is slotted for a screwdriver. That screwdriver slot is an assembly aid -- at the factory, the screwdriver slot helps with installation of the impeller onto the threaded end of the motor's shaft.

As a disassembly aid, the screwdriver slot is pretty much useless. After much installed service, the impeller will be very tightly in place on its thread. The screwdriver slot will not afford the sort of reliable torquing engagement that would be needed to successfully unscrew the motor's shaft from the impeller.

The assembly is simply not designed for non-destructive disassembly. It's designed for ease of assembly at the factory, and maintenance-free service. Once it fails, it's replaced as a unit, and it's 'game over' for it.

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Foot Switches

A foot switch can be a handy thing to have on hand in the workshop. I built this crude one from odds and ends long ago.

Much nicer ones are available ready-made from tool outlets, and the price is not unreasonable.

A foot switch is useful when you have a machining process lined up that requires both hands for control of it at all times. I recently had a boring job on the wood lathe like that, and introducing the foot switch to it made a somewhat dicey procedure into a relatively safe one.

'Just thought I'd mention it.

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A Welding Cart

The workshop has acquired a small welder.

All well and good, but it turns out that these little welders are a right mess of a thing to manage.

Cables all over the place, whether the thing is in use or not.

So, here's my solution.

A little purpose-built cart that tames the cables, and gets the welder up off the floor and ready for use wherever it might be needed.

Much better.

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Delta Model 36-070 Mitre Saw

My son acquired an old specimen of the subject mitre saw recently for very little money, and it looks like he got lucky -- the saw did a useful job for him on some renovation work at his home. Here's a view of the machine.

Since he has no immediate further need of the saw, we thought it would be a good idea to give the machine a teardown, inspection and some TLC, so there'll be no surprises come the next time the saw is needed.

This post will serve to document my work on the saw. The material that shows up here may not always be in the most coherent, linear order; I'm not claiming to create a proper service manual.

Motor Brushes

Brush access is good. Remove three M4x16mm truss head threading screws, and you can pull off the motor's end-cover.^[1] That gets you to here.

When removing brushes that will be re-installed, it's a good idea to unambiguously mark the holders and brushes, so you can get them back in place exactly as they were. Old brushes will have mated themselves to their original installation, and will last longest if returned to that installation. Just make some dot marks with an engraver to tell you what goes back where.

The brushes from this motor look fine -- evenly worn, and with plenty of length left to go.

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Blade Removal

Remove the blade guard to gain access to the blade's fastening screw.

There's a single M6 hex socket head cap screw that secures the blade guard adjustment link.

Remove that screw with a 5mm hex key, and it's pretty obvious from there on how the blade guard comes off.

A 13mm A/F hex washerhead screw secures the blade.

The screw has a left hand thread. To remove it --

• Lock the saw's arm in its storage position. (There's a locking plunger at the upper right side of the pivot column.)
• Jam the blade with a scrap of hardwood.^[2]
• Turn the screw clockwise.

Like so.

And if it weren't for the seven chipped teeth, this saw would have a very nice 40-tooth Hitachi blade on it.

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Motor/Gearbox Removal -- FRIDAY, JANUARY 23, 2015

Three M5x75mm screws secure the motor/gearbox assembly to the saw frame.

I'll clean everything up with compressed air, then decide whether I should open up the gearbox to re-grease it.

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I decided to leave the gearbox unopened. Given the condition of the brushes, there can't be a lot of run time on this unit, so there's really no compelling reason for me to relubricate the gearbox at this time.

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Blade Guard Adjustment -- SATURDAY, JANUARY 24, 2015

When we got the machine, its blade guard was inoperative -- the guard was jammed in its fully raised position. It turned out that the guard had been deliberately mis-assembled to disable it, and keep it raised at all times. Now that I have the guard working, I think I see why the original owner disabled it.

The guard's default geometry is such that guard operation adds a little to the force needed to start lowering the saw to make a cut. There's an adjustment that can be made to correct that. Here's a view of the guard's at-rest state as the factory no doubt sets it up.

Note that the guard is fully lowered/closed; the rear edge of the guard is stopped against a small, round bumper. Opening the guard from that position takes a perceptible bit of force, and a user might find that characteristic of the guard annoying.

The at-rest position of the guard can be adjusted so that the guard never fully closes, and that does away with the effort needed to start the guard opening. The attendant loss of guard protection is minimal.

To make the adjustment, loosen off the screw in the middle of the short link at the left with a 5mm hex key. Alter the guard's at-rest position so the guard is partly open when at rest, and retighten the screw. The guard's new at-rest position will look like this.

Note that the rear edge of the guard no longer contacts the bumper -- it comes to rest about an inch away from the bumper. By introducing that partially-open condition to the guard's at-rest state, the effort needed to start further opening the guard is made negligible.

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Notes:

[1] All three screw well bottoms were broken out of the cover on this unit. The same thing probably happens to all of them. I glued the well bottoms back in place with CA adhesive. Here's a view of the inside of the cover after repair.

Update -- SATURDAY, JANUARY 24, 2015

That repair failed. I redid the repair by using long enough screws to secure the cover by its outer end surface, like so.

The hardware complement there is:

• 1x No. 8 x 1 1/4" flat head wood screw.
• 2x No. 8 x 2" flat head wood screw.
• 3x 3/16" fender washer.
• 1x No. 8 cup washer.

End of that problem.

[2] Alternatively, you can hold the blade from turning by means of a 5mm hex key inserted into the motor's shaft-end at the right side.

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Christmas Tree Stand Clamp Screw Thread Marginality

How's that for a blog post title -- "Christmas Tree Stand Clamp Screw Thread Marginality"? It's a bit wordy, but it does convey the problem.

This Christmas tree stand has a clamp screw thread that's all but fully stripped.

The M8 screw won't apply pressure when tightened -- it just skips its female thread to no effect. (It never ceases to amaze me how manufacturers can't seem to master the simplest aspects of low-tech goods, yet they can produce high-tech items of stunning precision and perfection. It's a mystery.)

The female thread that's at issue here was poorly formed in thin material, hence the marginality.

What I'll do is fabricate a rectangular nut-plate from 3/32" thick steel flat. That will give me a nut that's inherently restrained from turning as the screw is turned. The nut-plate will tuck away neatly in its recess, and won't even be visible.

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And here's the nut-plate fabricated and in place.

End of problem.

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Not Quite -- SATURDAY, DECEMBER 31, 2016

The screw on the opposite side developed the same problem this year -- I gave it the same treatment as last time to repair it.

The root of the problem is not entirely with the female threads; the M8 screws are considerably undersize, contributing to marginal thread engagement. If there's a recurrence of the trouble, I'll replace all four screws as well as provide new female threads.

The stand's design is good, but the manufacturer's execution was poor. Properly made, one of these stands could last for generations.

One  wonders how many of these stands failed in this manner, and ended up in landfill. The waste is enormous, but then it's waste that makes the economy go round.

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