Friday, December 31, 2010

A Spray-Painting Turntable

I know it's ugly as sin, but it's a very helpful little piece of gear for spray-painting.

In a previous life, it was the base of a two-level lazy Susan spice rack for a kitchen cabinet. It eventually got fired from that job, so I snagged it and put it to work as a spray painting assistant.

It has the virtue of being very free-turning; it doesn't fight me at all as I reorient whatever I'm painting on it.

Here's a photo of a barbeque part I've placed on it for repainting. (The factory's paint job left a bit to be desired.)

That primer coat was a breeze. The turntable makes it easy to adjust an item's position any which way for spray painting it uniformly.

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Many items to be spray painted can be devilishly awkward to support. The accessory pictured below has proven very useful for such things.

I cut a disk from particleboard to just fit the turntable, and attached a Record No. 0 (2 1/2") mechanic's vise to it; all sorts of things become possible.

There's always some way to arrange to support a thing to be painted, and the vise is heavy enough that it can hold some very unbalanced items without being tippy. Some things, like the faucet shell pictured below, make it easy.

The faucet shell has a couple of 10-24 female-threaded bosses in it for securing the innards. So, a bit of threaded rod and a locknut were all that was needed here.

Tubular items, like a handlebar from a piece of yard gear, lend themselves to this sort of treatment.

In actual use, I cover the vise with newspaper to spare it the indignity of catching the spray fallout. Note the hole in the disc just in front of the vise's handle. That's for hanging the thing on a nail from a joist when it's not in use.

It's a versatile piece of gear that's not at all difficult to make.

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Thursday, December 30, 2010

Drain Auger Rental or... Credit Card Frawd

[I misspelled ‘fraud’ on purpose because I really didn’t do anything fraudulent; I just bent the rules a little. Rule bending can be very helpful when you need to get something done.]

This is a companion piece to “Leverage”, wherein I tell of my struggle with a three-inch iron pipe drain clean-out plug.

Once the plug was out, it was time to go rent a drain auger from the Home Depot. That prospect brought me up against the fact that I don’t have a credit card, so I borrowed my wife’s card. I don’t have signing authority on her card, but I wasn’t going to let a little detail like that interfere with a plan.

The Home Depot had quite a selection of drain augers; a hand-cranked one, and a couple of motorized augers – I think there was even a gasoline-engine-powered one. At $22.00 for a four hour rental, I figured the hand-cranked unit would do fine, and I took it up to the counter.

The counter guy asked for my name and keyed it into the computer. I showed up on the computer from the last thing I’d rented some years ago. He asked for a credit card and I handed him my wife’s card. He looked at it and of course the first name didn’t match. I quickly explained that it was my wife’s card. (I didn’t volunteer the information that I don’t have signing authority on it.) That was ok with him, and he proceeded to process the rental contract.

They charge ten percent extra for damage/breakage insurance, and I was told that if I bring it back filthy, there’s a fifty dollar cleaning fee, [!] so hose it off when you’re done. They throw in a pretty decent pair of canvas and leather work gloves, which takes the sting out of the insurance fee a bit. Anyway, onto the truck and home it went. Here’s a photo of it on the job, with its fifty foot coil almost fully deployed

It’s a well thought out, well constructed piece of gear. There’s a label on it with the name “X500 Snakentainer”. It’s made in the USA by the General Wire Spring Co. of McKees Rocks, PA. And here’s a photo of the machine’s business end:

Perched on its nose is an auger bit that came with it. One screw is all it takes to change bits. The bit that’s installed on it is called a 'boring gimlet', though the Home Depot guy called it a 'retrieval tool'. I ran through the pipe with that first, then followed up with the auger. It appeared to do the trick. So, outside for a quick hosing off and back to the store.

Back at the store, it was time to settle up the bill. I wasn’t worried about being hassled over the credit card that I had no business using; by now, the card had served its purpose and I could just settle up with cash if it came to it, but I thought I’d see how this would play itself out.

The guy already had the credit card’s ‘imprint’, so he didn’t need to see the card again. He embarked on processing the transaction – so far, so good – and then he got to where he needed a signature on the electronic tablet at the front of the register. I told him, “I really don’t have signing authority on this card, but what the hey.” He seemed unfazed, so I wrote my wife’s name on the tablet and pressed the “ACCEPT” button. Done. I could have signed it “Céline Dion” for all anyone cared. (And there’s an image to ponder – Céline Dion at the Home Depot renting a drain auger on a Sunday afternoon.)

So there we are. When the rules need bending, just be up front and forthright about it. People will take you for an honest rule bender, and just let it go by.

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Wednesday, December 29, 2010

Hoover portapower Vacuum Cleaner Overhaul

I had sworn off repairing old domestic vacuum cleaners. Most of them are such pieces of crap to begin with that they're more aggravation than they're worth. But my workplace was tossing this Hoover portapower, and I thought I'd make an exception for it.

As compact vacuum cleaners go, these are a pretty decent unit. Hoover stuffed a full-size, two-stage blower into that housing, so the machine is not feeble. It's a proper vacuum cleaner.

I was told that this one needed motor bearings. That turned out not to be true, but I tore it down anyway to clean and fully inspect it, and lubricate the unsealed rear motor bearing. It's a very straightforward design. There's only one press-fitted component -- the rear motor bearing -- and that didn't need replacement.

Per my usual practice, following is a largely unillustrated sequential procedure for getting the motor out and apart. Unless otherwise indicated, the fasteners are all No. 2 Phillips recess.

1. Filter Bag
> Unlatch and open the 'door' where the hose connects. The bag can be pulled out.

2) Left Side Cover
> Two No. 10 x 3/4" pan head threading screws in the handle.
> Four No. 10 x 2 3/4" pan head threading screws in the body.
> The cover lifts away straight off.

3) Motor Black Wire at Switch
> The on/off slide switch just lifts out. The underside of the switch has a plastic cover that comes off easily. The motor's black wire is connected via a miniature spade connector. Pull it off.

4) Motor White Wire
> Cut and discard one ty-wrap.
> Cut off the top-hat crimp connector. At reassembly, use an orange wire nut to restore the connection.

5) Motor
> Lift it out. NOTE that its white wire emerges at the right side (down in its present orientation).

REASSEMBLY NOTE for the following two items:

There's an opening in each brush holder that will admit a slender spring hook. That enables you to hook the brush's spring and hold it retracted while you get the brush holder back in position -- a big help.

6) Underside Brush Holder (Black Wire)
> NOTE: Keep the holders pressed against the motor's frame as you remove each holder's screw. When the screw is out, pull the holder straight away, else the spring-loaded brush is liable to tilt the holder and jam it in place.
> One No. 6 x 5/8" pan head threading screw.

7) Top Side Brush Holder (Blue Wire)
> One No. 6 x 5/8" pan head threading screw.
> One 90° spade terminal connection.

8) Rear Shock-Mount Ring
> Slip it off.

9) Front Shock-Mount Ring
> It's lightly adhered in spots, but it comes off easily.

10) Spindle Hex Nut (1/2" A/F)
> NOTE: It's a left-hand thread.
> Secure the motor in a woodworking vise by its flattened end where the brush holders were.
> Put a 1/2" open-end wrench on the nut and hold it steady.
> With a plain slot screwdriver with a perfectly fitting, perfectly ground tip, turn the motor's shaft CCW.

11) Oversize Flat Washer

12) Blower Cover w/First Stage Blower
> Four No. 8 x 3/8" pan head threading screws.

13) Second Stage Blower w/Oversize Flat Washer and Spacer Bushing

14) Oversize Flat Washer

15) Ring Washer

16) Motor Disassembly
> MARK the three sections with an engraver or centre punch. Even though they appear to be symmetrical, it's a good practice to always get things back together exactly as they were.
> Two 10-32 special hex nuts, 3/8" A/F.
> Two 10-32 x 2 1/4" hex head screws, 5/16" A/F.
> The motor can come apart and the armature can be pulled out now. There are two loose compression springs over the screws that are there to keep the field winding assembly biased against its seats.

17) Front Bearing
> There's a retainer with eleven little folded-over tabs holding it in place. Pry at the tabs with a small screwdriver to free it. Some of the tabs are liable to break off. That's ok. There's a better way to reinstall the retainer.
> The bearing is a slip fit in the end bell.
> The bearing is an NHBB 608D, sealed both sides, 8mm bore x 22mm O.D. x 7mm width. This is a widely used size of bearing that should be easy to find a replacement for if need be.

18) Rear Bearing
> It's a press-fitted needle roller bearing, INA SCE 65S, 3/8" bore. This could be a more difficult-to-get item were it to need replacement. And were it to need replacement, it's very likely that the armature's rear shaft stub might be beyond recovery as well, at which point it's game over for the motor.
> With the field winding out of the rear bell, wash the bell with its bearing in a parts washer and thoroughly blow it dry. Pack the bearing with grease. I'm partial to Canadian Tire's Wheel Bearing & Chassis Lubricant grease for this sort of thing.

19) Clean and blow the dust out of everything. Clean the commutator with lacquer thinner.

20) Front Bearing Retainer
> The folded-over tab arrangement can't be relied on for re-use. Break off any tabs that look ready to break off. Break off tabs A/R to get a balanced placement for three 4-40 x 1/4" screws. Install the retainer with the three screws and three No. 4 flat washers from outside. On the inside, install three more No. 4 flat washers and three 4-40 hex nuts w/blue threadlocker. Tighten firmly. Here's how it looks when done.

That's about it. The machine can be reassembled.

I don't know what to make of the story I got that this thing needed bearings. From the appearance of the brushes and commutator, this motor can't have very many hours of run-time on it.

Here it is ready to be closed up. Note the orange wire nut that's taken the place of the factory's crimp terminal.

It's a well thought-out machine. The wiring lays are roomy and neat; it will go together without a struggle.

Something I didn't mention earlier when I encountered it was a stripped female screw thread in the plastic boss for one of the long housing screws. This post tells of a repair method for such occurrences.

I buttoned it up, installed the filter bag and tried it out. It runs beautifully, and should have years of life in it yet. I just need to get it a new filter bag. The one in it looks pretty ratty.

So, that was time well spent. Now I can swear off vacuum cleaners again.

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FRIDAY, APRIL 15, 2011

Addendum -- New Filter Bag

I found a vacuum cleaner shop near where I work that had a new replacement bag. Here it is. The old ratty one is on the left.

The guy wanted twenty dollars for it, which I thought was a bit much, but I wasn't about to dicker. A cash purchase from his shop right there, right then saved me a lot of business and commerce codswallop that I can always do without.

I don't know the part number of the thing; the transaction was done without paperwork -- a bit of underground economic activity. The shop owner unloaded a piece of old stock for cash that the authorities needn't know about, and I didn't have to pay any sales taxes. The shape of things to come, perhaps.

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Tuesday, December 28, 2010

Sleeve Nuts

These things don’t deserve their obscurity; they’re quite a useful fastener. That’s my entire stock of them in the photo – they’re M4. I can’t recall how I came by them, but I’m glad I did. A couple of them are just what I need for a repair to the housing of an old Hoover portapower vacuum cleaner. If I didn’t have these on hand, I’d have to go to an industrial supply outfit like Spae-Naur for them, and buy a package quantity of 50 or 100.

The problem with the vacuum cleaner is a stripped female screw thread in a plastic boss. There’s a photograph of the complete unit here, along with a motor bearing replacement procedure. Here’s a close-up photo of the site of the stripped thread:

There’s nothing but a vestigial trace of the thread left. I have a method for repairing such threads in most cases, but it won’t work here because of the type of threading screw Hoover used. Permit me to digress a bit to point out some characteristics of threading screws used in plastic.

Pictured are the six screws that hold the vacuum cleaner’s housing together. They’re of two different types.

The two short ones are thread-forming screws. They make a female thread by displacing and compressing plastic material, not by cutting it. The resultant thread is quite strong because no material is removed to form it.

The four long screws are thread-cutting screws. They make a thread in much the same way as a thread cutting tap does. The resultant female thread is inferior to that achieved by the thread-forming screws, and is much more prone to stripping out. And when they do strip out, I can’t apply my thread repair method. That only works with thread-forming screws. So, I have to take a different approach to dealing with the stripped thread that’s at issue here, and that’s where sleeve nuts come in.

Sleeve nuts make it possible to fabricate tie-rods of just about any length with decent looking, unobtrusive ends on them – just what I need here. I’ll drill a 4mm clearance hole through that stripped out boss and out the side, then counterbore and countersink for one of those sleeve nuts. On the side where the original screw entered, the existing counterbore and screw hole accept a sleeve nut already with no modification required. Then I just have to determine the length dimension I need for a piece of 4mm diameter steel rod, thread both its ends and I’ll have a neat repair for the ruined thread.

Here’s the side of the housing made ready, and with a sleeve nut trial-fitted in place:

The finished appearance will be quite acceptable -- nothing cobbled up looking about it at all. Now it’s time to make the tie-rod.

I'll be die-threading a rod that's exactly 4mm in diameter with a 4mm die here, which is to say I'll be cutting a 100% thread. I can get away with doing that on a diameter this small, but on larger diameters (say, 6mm and up) cutting a 100% thread is a poor practice, and is likely to result in a rough-looking thread that's more difficult to cut than need be. It's wise to take a few thou off the diameter of larger rods with the lathe before die-threading them. Just how many thou gets a bit intricate. A publication like Machinery's Handbook is a good reference to have at hand for dealing with such questions.

Here's a method I came up with for die-threading small diameter rods. It beats the orthodox method by a country mile. (The chuck has to be tightened very firmly.) You'll find it much easier to start and cut an external thread this way than by using a die-stock. For split dies, when you want to make use of the die's adjustability, you can still use a die-stock; just clamp the die-stock w/die in the vise.

And finally, here's my tie-rod ready to take the place of the screw that was in a stripped-out thread.

I've installed one nut with blue threadlocker, so what I have in effect now is a long screw and nut.

I'm quite pleased with that. It's an excellent example of what can be done with sleeve nuts.

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