Thursday, September 30, 2010

The Poor Man's Day-Timer

I suppose if you're a member of parliament, or a mayor, or a corporate executive or a real estate agent, you need a Day-Timer to keep track of all your appointments and contacts and deals-in-the-works and what-have-you. But I lead a simple life; politics and business and commerce are not for me. I can get by with a dirt-cheap, home-made, shirt-pocket notebook. Here's a method for turning one sheet of office paper and three staples into a neat little 16-page notebook for keeping track of all the pressing chores and obligations in your life.

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Take a single sheet of letter-size paper. Fold it in half. Fold it in half again. Fold in half again. Do the folds as precisely as you possibly can, and press the creases as sharply as you possibly can.

Now, with a regular office stapler, install three staples along the thing's 'spine'. Sight the stapler's staple-emergence position relative to the 'spine' as carefully as you can to get a good result.

Now, take a small utility knife with a sharp new blade in it, and slice the three folds that are preventing it from behaving like a booklet. Here's how it all looks at the point where you're about to slice the folds:

You'll end up with a smooth little 16-page notebook for jotting down all your chores, as you can see in the final photograph.



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Saturday, September 25, 2010

Back-Up Washers for 3/32" Hollow Rivets

When using hollow ("Pop") rivets to fasten leather or fabric, you need to slip a close-fitting washer (back-up washer) onto the rivet before crimping it, so there'll be an unyielding encirclement for the rivet to 'peen' against. Flat washers dimensioned specifically for the purpose are available.

I needed back-up washers for 3/32" rivets this morning, and I wasn't about to waste time and fuel to go shopping for them. I looked in on my limited stock of No. 2 screw size items, and there I had a supply of No. 2 flat washers. They're 3/32" (0.09375") inside diameter, but they're not a slip fit on 3/32" rivets. Running a No. 41 (0.096") drill through them solved the problem. They worked perfectly. Pictured below is how I held them for drilling:

There's one little downside to this -- the washer gets marred by the Vise-Grip jaws. Aside from that, though, the method works fine.

If I ever come up with a good non-marring way to grip the tiny washers for drilling, I'll append it to this post.

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SUNDAY, DECEMBER 18, 2011

Addendum -- A Non-Marring Way to Grip Small Washers

I found a way to do this. You need a spare 3/8" gear chuck, and a smooth, hard surface like the back of a Record mechanic's vise.

Have the chuck opened up to accept a diameter slightly greater than that of a washer.

Invert the chuck over top of a washer and carefully snug up the chuck by hand. You'll end up with this.

Tighten the chuck some with its key, and you're set up for enlarging the washer's hole slightly.

I've noticed that some of the 3/32" rivets I have on hand are a wee bit oversize, and a No.41 drill isn't quite big enough. A No. 40 (0.098") drill is needed for those.

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A Riddle

At the risk of appearing a bit dense, I pose this question in all seriousness. The answer is not readily obvious to me.

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Suppose you have a shaft that's exactly 1.000000" in diameter.

And suppose further that you have a hub with a bore of exactly 1.000000" diameter.

Is the shaft a slip fit or an interference fit in the hub's bore?

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Sunday, September 19, 2010

A Stubby Jack Lever

Sometimes when jacking a vehicle with a small floor jack, you have to get the jack quite far under the vehicle for it to reach the jacking point that you're after. Then you go to insert the lever and start raising the jack, and you realize that the standard lever is too long to give you anywhere near full piston strokes with the low clearance you have above the jack. What's needed in those situations is a stubby lever that'll give you enough leverage to get things going. Once you get the jack raised, and a bit of jacking begun, you can switch over to the standard length lever and carry on.

That nasty-looking piece of 3/4" diameter steel rod is what I've been using. Since I've been sprucing up some of my workshop's gear, I thought I'd prettify it a bit and install that 10-24 screw-eye at one end for hanging it up when it's not in use. There'll be an interesting point to be made here about cutting female screw threads with a tap. I'll get to that shortly. First, I'll chuck that rod in the lathe, square off and chamfer the ends and clean it up to make it fit for painting.

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There. That's done. Here's the rod chucked in the lathe, centre-drilled and ready for boring with a tap-size drill:

Cutting threads in blind holes to any appreciable depth is fraught with peril. To install the full length of that screw-eye's threaded stud, I'd need a 5/8" depth of female thread in the rod. To attempt to cut that deep a thread with a tap, even in mild steel like this, would be foolhardy -- begging for a broken tap. (I'll leave it to the reader to guess how I've come to know that.) So, I'm going to cheat a bit here.

First, I'll shorten the screw-eye's stud so that I'll only need a 1/4" threaded depth. That should be doable.

And second, I'll drill the hole oversize of the normal 75%-thread drill size you get from the charts. All the thread is ever going to have to bear is the weight of that rod hanging from a hook. A 50% thread will more than suffice here, especially if I assemble it with blue Loctite. Also, it doesn't have to be a blind-tapped 1/4" deep hole; I can drill deeper than needed and thread it in one go with only a plug tap.

For a suitable drill size for a 50% thread, I only have to look up the pitch diameter of a 10-24 thread. A thread's pitch diameter is its diameter at a point half way between the crests and roots of the thread. For a 10-24 thread, the figure is 0.163". The nearest number size drill is No. 20 (0.161"). That will give me just a tiny bit more than a 50% thread, while considerably easing the load on the tap. I'll drill 5/8" deep to give clearance for the tapered front portion of the tap, and this should work out fine.

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And here we are with a deep enough thread and an unbroken tap:

(You can see the shortened screw-eye stud in the shot as well. That material protecting the rod from marring is 0.020" thick scraps of aluminum exterior window casing material. It's excellent for the purpose.)

To have gone any deeper would have been pushing my luck big time. I should also mention that for both the boring and the threading operations, it's wise to back out the drill/tap frequently to clear chips.

Anyway, my point here is that while orthodoxy is all well and good, it's not a strait-jacket. When it comes to tap drill sizes, you're at complete liberty to deviate from the 75%-thread drill size when a situation calls for it. Consider what the thread is actually going to be asked to do. In this case the answer was "not much" -- there was no need for a 'strong' thread, only an adequate one. An adequate one was doable. A strong one might not have been.

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I'll give that rod a nice gloss black paint job before installing the screw-eye for good.

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And here's the lever out on the job site. (I should have painted it orange for this photograph.)

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A Speedy Drill Press Depth-Stop

From the "Why didn't I think of this a long time ago?" department comes this speedy depth-stop modification for an old threaded-rod-style drill press depth-stop.

Pictured above is the depth-stop on my venerable Beaver drill press as the factory supplied it. It works fine, but it's a tedious thing to use. It takes a lot of knurled nut twirling to set and reset it.

The other day I needed to use it and I asked myself, "What's the diameter of that threaded rod that's so conveniently flattened on two opposite sides." It turns out it's 1/2"; just the sort of diameter that I'd be likely to have a shaft collar for in my 1/2" diameter stuff bin.

Sure enough, I had a 1/2" shaft collar, and a nice 5/16"-18 x 1 1/2" hex socket head screw to use for an extended-reach setscrew. I spun off the two knurled nuts, installed the shaft collar and now I have a quick-set depth stop, like so:

I wonder what's the sum total of time I've spent over the years twirling those two knurled nuts. It's probably just as well that I have no way of knowing that.

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Monday, September 13, 2010

A Sanding Board

The sanding board pictured is the converse of a sanding block -- the abrasive stays puts and the work the gets moved against it. The cast/machined router base in the photograph is what led me to come up with this.

I bought the router a long time ago, used it once for something inconsequential, then had no further use for it for quite a while. Then something came up that called for a router mounted in a stand. I acquired a stand and mounted the router in it. Something looked amiss. Peering across the surface of the router table, I could see that the table had a pronounced convexity to it. I dismounted the router and the convexity went away. I put a straightedge across the router's base and there was the source of the convexity -- what was supposed to be a dead flat metal plane was pronouncedly convex; not too impressive.

I figured it was far too late to take the router back to Sears, so I set about devising a way to fix it. I had this piece of dead flat 1 1/16" thick melamine-clad particleboard on hand (I know not where it came from.) and it struck me that it might make a fine sanding board. A bit of work to devise a clamping scheme for the paper got me the board you see in the photo, and it worked just fine. A sheet of medium-fine aluminum-oxide paper got the router base flattened in short order.

Since then, the board has proven useful again and again. Many small objects are much more easily sanded by presenting the work to the sandpaper, rather than by presenting the sandpaper to the work.

The sanding surface available is 8" wide; only 1" of a 9" x 11" sheet's width is lost to the clamps. The clamp angles in the photo were made from some ancient salvaged mini-computer cabinet parts. 1/8" x 1/2" steel bar stock would work as well; you just want the clamps not to protrude up above the surface of the sandpaper. I installed six 6-32 tee-nuts in the board's underside for the clamping screws. Clamping with wood screws directly into particleboard would be a bad idea; the threads would eventually strip out.

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Sunday, September 12, 2010

A Floor Jack Hanger

I like tools to be hung up where I can see them, and get at them instantly. Rummaging about for things in drawers and cubbies is a nuisance, and the last time I had to retrieve my floor jack from its lair I decided that's about enough of that -- it's time to make this thing a hanger.

That steel strap will serve as material for the actual 'hook'. And since nothing goes to waste around here, I'll use that wretched chunk of 2"x 4" for part of it.

First thing to do is to saw that wood into a presentable rectangle, 1 1/16" thick. Resawing 'trash' wood like this often reveals some quite spectacular figuring. That chunk of wood was once part of a living tree, and I think you can really see that in this result:

So I have my neat rectangle, 1 1/16" x 3 1/4" x 5".

The steel strap is salvage. In a former life it was a shipping restraint for a Qume daisywheel printer . I have about a dozen of them, and I'm ever so glad I thought to snag them when I had the opportunity. They're very useful material.

They're galvanized mild steel 1 1/2" wide by 17 3/16" long overall. The length available between the two punched holes is 14 5/8". The thickness is 0.079" (about 5/64" or 2mm for all practical purposes). And stating a sheet metal thickness brings me to the subject of sheet metal gauge numbers. A wee digression is in order.

Sheet Metal Gauge Numbers

I dislike sheet metal gauge numbers for the simple reason that no one ever specifies which gauge they're referring to. There are at least four. There are six wire gauges that I know of.

Here's what "Machinery's Handbook, 21st Edition" has to say about gauge numbers:

"Much confusion has resulted from the use of gauge numbers, and in ordering materials it is preferable to give the exact dimensions in decimal fractions of an inch."

Amen to that. If I ever do state a gauge number in this blog, I'll specify which gauge I'm referring to, and I'll still include the actual thickness dimension.

With that out of the way, it's time to form a hook for the jack's 14mm diameter front axle to hang by. I've squared off one end of the steel strap to get rid of the portion with the punched hole. Now I have to rig a means of bending it into a hook shape. Here's what I came up with:

Crude and primitive, but it worked. (That 's 1/2" threaded rod.)

Two things about this setup were key to it succeeding:

a) The hardwood blocks for the c-clamp to seat on. The upper ends of the threaded rods had to be absolutely immobilized. The hardwood blocks made it possible to install the c-clamp squarely and securely.

b) A very firmly tightened vise. It's a good practice to periodically attend to a vise-screw's lubrication, especially at the 'head' of the screw where it bears on the front jaw. The force load at that point is enormous, and the bearing surface under the screw-head is relatively small. The screw-head needs to be well lubricated to rotate freely under load, and let you apply all the torque you can to good clamping effect.

If you look closely at the lower edge of the steel strap right at the front jaw of the vise, you can see that my forming job didn't come out dead straight. That was fairly easy to correct by clamping the short end of the hook in the vise and levering the long end to correct the flaw.

The rest of the job should be fairly straightforward -- cut the hook to a suitable length; lay out and drill screw holes as required; assemble and install.

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And voila, here's the jack hanging on the wall where I can get at it right quick:

The three screws attaching the hook to the wood block are N0. 12 x 1" pan head sheet metal screws. The two Tapcons are 1/4" x 1 3/4" hex heads. That's a very secure installation.

I counterbored for the Tapcons' heads because the 1 1/16" thickness of the wood block was too much for a 1 3/4" long Tapcon. Tapcons are supposed to achieve 1" of penetration into concrete for a correct installation.

If it looks to you like the Tapcons' heads aren't centred in their counterbores, it's because they're not. Getting holes drilled accurately placed in concrete is diabolically difficult. I had to drill 5/16" holes through the wood block to give me some adjustment latitude for plumbing the block, and it's still not perfect. That's the one flaw in this installation; otherwise I'm quite pleased with it.

I have the feeling, though, that I may have tempted fate here. The truck is liable to reward my work to make the jack readily accessible by coming up with a flat tire.

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Addendum

It was really bugging me that I hadn't got this mounted perfectly plumb. I clamped a length of 1" x 2" hardwood to one side of it, parked a small level on its top surface, loosened it off, levered on it to 'adjust' it and tightened it back up. It's ok now. I feel much better.

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Saturday, September 11, 2010

Truing a Puller

One of my workshop's operating principles is "you can never have too many pullers". So when I saw this 8" puller on special at Princess Auto I made sure I got myself one.

These inexpensive pullers from offshore do give you a lot of metal for your money, but they tend to come up a bit short on precision, and are likely to need a little attention before they'll work as well as they ought to.

The shortcoming with 3-jaw pullers that I keep seeing is in the uniformity of the lengths of the jaws. When the lengths are uneven, the tool sets up crookedly. The defect doesn't render the puller useless, but it does make it clumsy to set up (and pullers are clumsy enough things to set up when they're perfect) and it does impair the puller's effectiveness -- the puller's force is off at an angle to the subject axis; that's not helpful.

To check the jaw length evenness, dismount the jaws and rack them up on a close-fitting bolt or length of threaded rod. Any length unevenness will be obvious.



I think I'll have to ask you to trust me on this, but that near-side jaw at the lower right is shorter than the other two. The puller will set up crookedly. This puller is actually not too bad in this regard; I have a 6" puller that was much worse. (Why the factory cannot or will not amend its methodology to correct this is beyond me.)

You need to also examine the jaws at the other end, and assemble the jaws using the other hole and examine both ends. In this case, the other end was good enough not to need attention; there's just this one short jaw that wants grinding to even it out with the others.

Here's the rig I came up with for grinding puller jaws:



That angle grinder has an M8 threaded hole on either side for a handle, so it was a simple matter to make this prop arrangement that presents the wheel at an angle suitable for grinding the hook-faces of puller jaws. The next photo shows the process in action.

This is not precision machine shop work by any stretch of the imagination; it's rough, nasty, 'by guess and by gosh' work. You'll find it a bumpy ride as particles lodge is the wheel now and then and kick the work. Check your progress often, and don't expect a pretty outcome. The result pictured below is where I stopped and said "good enough".



As I said, it's not pretty. The sheer size of these jaws made this job more difficult than others I've done, but I'll have a better puller for having done this.

The final photograph is of the jaws of a 6" puller that had very uneven jaw lengths, much worse than this one's. On that puller, one jaw was much longer than the other two, to the point where I would have seriously weakened the other jaws had I ground them to align with the long jaw.

I got around that by fashioning a shim that I could crimp onto the face of the long jaw. It worked well. I pulled a brake drum with this unit the other week and the puller set up nice and straight. It certainly wouldn't have prior to the grinding and the addition of the shim.



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Grinding Wheel Dresser

At the risk of appearing to be a shill for Lee Valley, I must give credit where it's due and report on their diamond grinding wheel dresser No. 70M5003.

I'm impressed. The thing works nicely.

The new wheel pictured was almost 0.020" out-of-round, so I thought it would make a good test subject. With very little work I got the wheel to within 0.005" of round. I dressed two other wheels while I was at it and both came clean and 'smooth' easily.

The tool works best when it's swept from side-to-side, using the full length of the dressing head. You might want to wear a shop apron while using it. By the time I was done with the out-of-round wheel, I needed a good vacuuming in front.

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Addendum

This pretty much renders my clunky old star-wheel style dresser obsolete. I must find a good use to put it to.

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Monday, September 6, 2010

A Micrometer Stand

When you acquire a micrometer and begin making use of it, you soon discover that miking tiny parts with it is a very clumsy bit of business. You truly need a third hand, and the stand pictured does the job.

Before I built this, I looked into getting a ready-made one. They can be had, but not nearby or inexpensively. It somewhat surprised me that such a useful accessory for a micrometer would be such an obscure item.

Anyway, since I much prefer working to shopping, I went on a scrounge around my workshop and came up with the makings of a stand in short order.

The base is a steel, 3 1/4" diameter pulley. The pulley is heavy enough that the stand isn't tippy. A 4" spring clamp serves nicely for holding the micrometer. Two 3/4" corner braces and a few fasteners and washers provide the hinged mounting arrangement that permits adjustment of the micrometer's viewing angle.

The screw for the pivot-point is Loctited into a threaded hole in the lower corner brace, so the screw never loosens when the wing nut is loosened for adjustment. I should add a second screw or an interference-fit pin where the clamp is attached to its corner brace, so the clamp can't twist out of position sideways.

I won't hold my breath waiting to win any industrial design awards for it, but for the price it's been serving me well. (By the way, that oversize 1/4"-20 wing nut was once the cover fastener for a Ford Pinto's air cleaner. Think what you will of the Ford Pinto, they were good basic transportation, and they had fine air cleaner cover wing nuts.)

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Thursday, September 9, 2010

Addendum

I finally got around to doing what I should have done in the first place, I added a roll pin to the clamp/corner-brace attachment point so the clamp can't get torqued out of position.

This is a handy technique for securing interfaces against rotation when you have very little room for an additional threaded fastener. Drill one small hole, install a roll pin, problem solved.

That roll pin is tiny. It's 1/16" diameter x 3/16" long, but it's all that's needed.

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Sunday, September 5, 2010

A Watering Can Repair

The old garage-sale-find watering can pictured is a nice piece of gear. There's a brand name on it; "Garden Club". It must be pretty old because it was made in the U.S.A., and the U.S.A. doesn't do that sort of thing anymore.

The body of it is still in fine condition, but the nozzle is past it -- embrittled and cracked in many places. The nozzle in the foreground is a good salvaged one that I can adapt once I get the duct tape adhesive muck off the can's spout. (I'm not a big fan of duct tape. I've spent quite enough time cleaning up what it leaves behind when it's removed, and I don't recall ever having enjoyed it.)

The difficulty here is that the replacement nozzle came from a can that had a considerably larger diameter spout-end on it than this can has. I could just slather the parts with a silicone gasket maker and assemble them that way, but it would be a poor job. The key to using adhesives and sealants is to never ask too much of them.

What's needed is a bushing of sorts to take up the space between the two diameters. That will minimize the amount of adhesive required, and make for a snug, sturdy interface. Sometimes you get lucky with these situations, and it turns out that some piece of standard-dimension thin-walled tubing is close enough to what's needed. But here, I'm dealing with a couple of very odd diameters, so I'll have to fabricate what I need.

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Here's what I came up with:

That band was cut from a scrap of 0.020" thick aluminum window casing material, and rolled around a 9/16" socket wrench to form it. The replacement nozzle can just be slipped on over the band with a bit of force applied, so I've succeeded in taking up the bulk of the gap with solid material. The 1/8" diameter holes perforating the band are key to getting the strongest possible outcome here. I'll be using epoxy as an adhesive/filler.

What the holes do is they effectively turn two interfaces into one. The epoxy filling the male thread on the spout, and the epoxy filling the female thread in the nozzle won't be entirely isolated from one another. When the epoxy has cured, at every hole there'll be a tough, contiguous span of epoxy through the hole. So, there won't be two epoxy-adhered interfaces; there will be one aluminum-reinforced epoxy-adhered interface -- big difference. In normal use, the repair should be near indestructible.

Here's a shot of the inside of the nozzle (the sprinkler head is a snap fit and can be pried off fairly easily). You can make out the edge of the filler band, and see that the epoxy has formed a full and reasonably uniform fillet all around. That nozzle's not going anywhere without the can.

I'll leave that to fully cure overnight, snap the sprinkler head back on and photograph the finished item.

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And here's the finished watering can out with its pals:

A good outcome. You'd never know to look at it that the can and nozzle weren't made for one another. And the purchase price was all of twenty-five cents, no sales tax.

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Wing Screws

Everything has its converse -- vice has virtue; joy has sorrow; hex sockets have hex keys and wing nuts have wing screws.

Wing screws are easily fabricated when the need arises. The only complication is that most screw heads in any given thread series are too large in diameter to fit directly between the wings of a wing nut. (The examples in the photo are 10-24.) An exception to that is hex socket head screws, but I don't care for the finished appearance (upper left); the hex socket head is too bulky to look right.

But a few minutes at the lathe with an ordinary round head screw gets you a reduced diameter screw head that's in good proportion to the wing nut (upper right).

Assemble the two pieces with red Loctite threadlocker or CA adhesive, and tighten very firmly.

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Addendum -- THURSDAY, OCTOBER 10, 2013

If you need an M4 wing screw, but only have 8-32 wing nuts, just run an M4 tap through an 8-32 wing nut and you're away. M4 and 8-32 are very near one another in diameter and pitch. (M4 is slightly smaller in diameter than 8-32.) The M4 thread you get from tapping an 8-32 wing nut is entirely adequate for this application.

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