36 mm 8 point box wrench

Looks like a relatively accurate layout job followed by work on the drill press, die grinder and finish with a hand file to me.

Looks like a relatively accurate layout job followed by work on the drill press, die grinder and finish with a hand file to me.

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Mild steel can be sheared with a cold chisel by clamping it in a bench vise with the cut line at the top of the jaws. Start at a small drilled hole and angle the chisel. It's easier if the metal to be removed has been roughed nearly to size by drilling rows of holes.

Amazon shows other 36mm box and socket wrenches here: How is your battery project doing?

I bought a Weize 12V 18Ah LiFePO4 for a fairly reasonable $70 but the price soon jumped to $100. Although the terminals are different it fit well into an older yellow HF 5-in-1 power pack. I changed one of the cigarette lighter outlets into Anderson PP45 on thicker wires so a 300 or 500W Bestek true sine inverter will plug in, with less voltage drop. The pack already has a mod sine 120VAC inverter and an air compressor, the function I use most. The

300W Bestek is my answer to chargers and power bricks that may have capacitive AC inputs.

Much too much 8-)

I neglected to mention that the 1/8" thick requirement was to clear an electrical connector integral to the part. It'd take a lot of grinding to make a clearance window in a socket and it's kinda hard to file extra points in a socket. A flat stamped wrench is, if not essential, a much better starting point and hopefully cheaper too.

Since you ask, I'll post an update to the homepower newsgroup....

Thanks for writing, bob prohaska

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Yes, but I still need the starting material. If I have to buy _something_ I'd prefer it be at least close to the right size and shape.

Thanks for writing,

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Seems you are working on a Dynamo Hub?

They have a couple wrenches in stock that might be modded:

A different idea is to get a flat washer with maybe a 35mm hole. File inside of it to fit and then weld a handle on.

How about a big honking internal lock washer and weld a handle on. Maybe 1-1/4 inch?:

Might be able to find those locally at store...

In a pinch I'd probably machine something out of 4140HT for that. In fact I have several collet wrenches in my tool holders box where I did exactly that.

4140HT is more than hard enough for an aluminum fitting, and if I needed harder it doesn't have an overly complex heat treating recipe for something as simple as a box wrench. It might warp a little, but its just a wrench.

Visiting a local bike shop proved enlightening. It appears that a 39 mm 16 notch bottom bracket wrench is 39 mm groove-to-groove. That matches the 39 mm point-to-point size of the octagon nut. I'm not sure how well the wrench will clear the flats, but that can be fixed with a little filework. Much easier than starting from a blank piece of metal.

When told I was looking for a "TL-DH10" wrench the shop clerk found it out of stock as I did and eventually said it appeared to be dis- continued. If it's functionally the same as a standard bottom bracket wrench that would nicely explain why it's gone missing.

Unfortunately the bike shop didn't have a 39 mm bottom bracket wrench. At least I know what I'm looking for now....

Thanks to all for reading and replying!

bob prohaska

In a pinch I'd probably machine something out of 4140HT for that. In fact I have several collet wrenches in my tool holders box where I did exactly that.

4140HT is more than hard enough for an aluminum fitting, and if I needed harder it doesn't have an overly complex heat treating recipe for something as simple as a box wrench. It might warp a little, but its just a wrench.

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That's great if you have it. If not, discarded saw blades can be annealed and cut into flat shapes, then rehardened if necessary. A test piece cut from an annealed 6" carbide-tipped saw and rehardened scratched glass.

I got a stack of dull used blades from a kitchen installer who was cleaning out his work van.

For thicker stock you could try lawnmower blades and car leaf springs. I practiced blacksmithing, hardening and tempering on an old car spring, then bought a piece of new (no hidden cracks) 5160 spring stock from a custom shop. I thought smithing could be a good way to shape custom tools too large for my lathe and mill. It might if I had a lot more skill and practice, I've had better luck welding or bolting manageable pieces together. For example a sharp-cornered hex shaped opening can be cut in two halves with an end mill.

If I had to make one I think I'd lay out and scribe the 8 point pattern on blued mild steel, drill 1/16" at the points, hog out the middle with a hole saw and cut as close as I could see to the lines with a fine tooth hacksaw.

I'm not sure how important it is to make something so purpose built for this. Couldn't you take a rubber strap wrench (like for oil filters) and rip it down the middle to be narrow enough for your hub nut? I've taken off the caps from Shimano's internally geared hubs with strap wrenches to good success.

THAT sounds like to much work for me. I CNC all the stuff like that these days.

I remember seeing some giant wrench or nut made that way shown in a high school mechanical drawing class, and I thought to myself that it looked like a work of desperation.

Ok, I admit I have made wrenches fit an application with a torch, grinder, and/or file before. Like I said. It was a work of desperation.

The short answer is that I don't know yet. This particular hub was disassembled a couple of years ago by a mechanic at a local bike shop who was bigger, younger and stronger than me, using an open-end (IIRC) wrench. He ended up damaging some of the (very short) octagonal flats.

We were both astonished at how tight it was and that he didn't wreck it.

After cleaning the inside of the hub (and seemingly fixing the persistent scraping noise it made) I screwed the hub back together with relatively modest torque and a trace of grease on the threads to prevent galling.

If I'm lucky it'll come apart as gently as it went back together. However, the male thread is prone to rolling within the female thread. Geometrically it's like a tire that's loose and creeping on its rim. The male thread, being smaller, rotates faster than the female thread and so gets tighter.

By the end of the week I should know the answer to your question.

8-)

bob prohaska

THAT sounds like to much work for me. I CNC all the stuff like that these days.

I remember seeing some giant wrench or nut made that way shown in a high school mechanical drawing class, and I thought to myself that it looked like a work of desperation.

Ok, I admit I have made wrenches fit an application with a torch, grinder, and/or file before. Like I said. It was a work of desperation.

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Yes, it's the sort of project given to students to teach them dexterity and patience. I still do it because I still need those lessons, plus I can cut shapes by hand that I can't measure or cut on machine tools, especially on parts too awkward or delicate to clamp tightly. I'm getting good enough to make the light press fits in metal that I learned long ago to do in wood.

However I learned the hard way NOT to fit a car fender rust patch snugly. They need clearance to expand from welding heat.

If I had CNC I'd certainly use it, but my 1950's and 60's model shop machine tools don't even have DROs. I spend many years designing aerospace circuit boards and their metal enclosures on a CNC workstation.

I definitely have manual machines in the shop, but I love me some DROs. I even bought a DRO for the POS manual mill mold making video series. I'll probably stick it on the machine as a supplemental video after the 2nd project video in the series. (Probably a spindle upgrade after the 1st.) Been debating on whether or a DRO would be useful on the little turret lathe. I think not. Once a job is setup on it the stops should take care of that for repetitive work. I am prepared to consider it though.

I definitely have manual machines in the shop, but I love me some DROs. I even bought a DRO for the POS manual mill mold making video series. I'll probably stick it on the machine as a supplemental video after the 2nd project video in the series. (Probably a spindle upgrade after the 1st.) Been debating on whether or a DRO would be useful on the little turret lathe. I think not. Once a job is setup on it the stops should take care of that for repetitive work. I am prepared to consider it though.

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After machining a run of parts on a DRO Bridgeport at work I bought inexpensive scales for my Clausing and started making mounts and chip shields. Part way through I realized that what I make at home often attaches to something I don't have a dimensioned drawing for, so I have to cut to fit, for which the dials work well enough, corrections are typically a pencil line width or less. The last thing I made has a cutout for an old analog panel meter with mounting studs in a triangular pattern that I laid out with dividers. A pointed wiggler usually gets me within 0.005" of scribed lines.

My electronic enclosures are light aluminum or plastic that deforms a little in the vise and doesn't repeatedly zero the same way against the stop, so I use a left rear hole or cutout corner as the zero and scribe the layout onto a paper label. The analog meters have snap-on bezels that flex at the edges and weren't a reliable baseline to measure X - Y mounting dimensions.

When I forget where I am rulers graduated to 0.1" find the handle turns count.