# Grinding down flat wrench to use as cone wrench



## David C (May 25, 2011)

Hi peeps, DIY way to go for inexpensive cone wrench ?

I'd sure like to buy some, but they're way overpriced and I used them maybe 3-4 times a year. But I have a bunch of normal wrenches, so I'd figured I could simply grind them down to the thickness needed and have a full set for under $20.

3 questions :

1. Any reason why this would be a very bad idea ?

2. What's the ideal thickness I should aim for ? 2mm, 2.5mm, etc ?

3. When grinding down, should I grind only one side, both sides or the whole surface of the wrench ? So it doesn't interfere with the other wrench during use since you usually use 2 of them to adjust your cones and locknuts.

Thanks 

P.S. My time is free, and I have plenty to spare hehe.


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## Bro (Dec 20, 2010)

I found a set of Park cone wrenches online last week. They're double-ended, with one size on each end. I I got a 13/14 mm, 15/16 mm, and 17/18 mm wrench for about $15 American, shipped. There were a couple other sizes available, but I just ordered what I can reasonably see myself using. I've also got a couple of box-end wrenches, and it's possible to use those on the outer locknut on the hub. I just used the cone wrenches for the first time today, on a couple different wheels, and they work great.

I wouldn't want to grind down my wrenches. It's nice having a lot more material to give a bigger contact point with the nut/bolt so that the wrenches don't dig into soft nuts on high-torque applications, like on my bolt-on fixed gear wheels.


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## David C (May 25, 2011)

Good deal you found.

What I meant to state was that I already have many sets of both metric and SAE wrench, so that I can just pick up the sizes I need and grind them. Don't worry I won't do that to the good ones, which cost a lot more than $20/set. I already used cone wrenches, but they were not mines, just at the shops I worked and the bike co-op where I volunteer. I know they work great 

And I'm not sure at which point the hardness of both the wrench and the nut would be an issue, since it's hard to determine if the usual torque used on cones and locknuts would be enough to dent a regular grind down wrench. I know the cone wrench are hardened, which is why they cost a bit more, but they are still overpriced IMO.


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## nov0798 (Nov 27, 2005)

I have a whole set of ground wrenches, and they work fine. Cheap Harbor freight ones. Its not like you put alot of force on them.


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## KevinGT (Dec 25, 2012)

erik1245 said:


> I found a set of Park cone wrenches online last week. They're double-ended, with one size on each end. I I got a 13/14 mm, 15/16 mm, and 17/18 mm wrench for about $15 American, shipped.


Help a brother out! Where'd you find 'em?


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## TwoHeadsBrewing (Aug 28, 2009)

I did that with some paint scrapers. All you need is a dremel with a cutting wheel and grinder. I didn't do it for cost, I just needed the tool and was too lazy to make the 20 minute drive to the bike shop.


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## Bill in Houston (Nov 26, 2011)

David C! We thought you was DEAD!

Yeah, grind them down. Someone should say something about not overheating and ruining the temper of the steel. I think I would grind just one side so I could have a little offset in the head.


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## Bro (Dec 20, 2010)

KevinGT said:


> Help a brother out! Where'd you find 'em?


The info has been communicated via rep.


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## Ratt (Dec 22, 2003)

David C said:


> Hi peeps, DIY way to go for inexpensive cone wrench ?
> 
> I'd sure like to buy some, but they're way overpriced and I used them maybe 3-4 times a year. But I have a bunch of normal wrenches, so I'd figured I could simply grind them down to the thickness needed and have a full set for under $20.
> 
> ...


Pricepoint house brands are only $4ea, you just missed the free shipping week. The double ended ones aren't much more and usually come in pairs and handle 4 different sizes. I took the Performance brand double ended ones and ground the insides to make a wider for a larger nut. You rarely need 2 cone wrench, most the time a regular wrench will work on the outside nut.


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## David C (May 25, 2011)

Thanks. I'll see what I come up with this weekend.

I'll get you guys pictures too


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## wv_bob (Sep 12, 2005)

I vote to offset grind them, because I doubt a cheap wrench gets heat treated all the way through. If so, offset grinding would keep as much good metal as possible if you can keep enough material at the handle to keep the head on. It may have a tendency to break but at least it's just a cone wrench so you wouldn't be torquing on it anyway.

For thickness I'd say my Park wrenches are about equivalent to 16 gauge thickness, maybe a little more. That's about .060, pretty thin indeed. Depending on your parts you could maybe go wider. You just have to start grinding and stop when they work. :thumbsup:

You're going to need a bench grinder, or a lot of time. So if you use a big enough grinder to throw the wrench, be sure to stand so you don't hit yourself if it ever goes flying. :eekster:


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## reptilezs (Aug 20, 2007)

just grind em down offset for a little clearance but it doesn't really matter. cone wrenches are disposable in a shop environment


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## J.B. Weld (Aug 13, 2012)

Pick a decent wrench, it needs to fit the cone pretty well. Cones and locknuts are often (should be) locked together tight so even good cone wrenches get thrashed fairly easily. Since the wrench needs to be so thin it is important that the steel is hard, more so than on a standard wrench and I imagine you will lose a lot of the steel's temper during the grinding process. 

It is satisfying to manufacture stuff though and I've done plenty of jerry-rigging in my day. Good luck and have fun!


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## David C (May 25, 2011)

Thanks. I do have a bench grinder and all sort of fun tools. A surface grinder would be even better for finishing the work. I'm pretty good with a file too, so I think I'll have plenty of fun in the workshop this morning 

Pics to come.


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## customfab (Jun 8, 2008)

Grinding them down is going to make them even harder. A file won't be good for anything but removing burrs by the time your done. If you have an angle grinder I'd start with that with some 36 grit sandpaper on it. 

Personally I'd just go buy a set of combo cone wrenches though.


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## car bone (Apr 15, 2011)

David C said:


> Hi peeps, DIY way to go for inexpensive cone wrench ?
> 
> I'd sure like to buy some, but they're way overpriced and I used them maybe 3-4 times a year. But I have a bunch of normal wrenches, so I'd figured I could simply grind them down to the thickness needed and have a full set for under $20.
> 
> ...


I just got pedros. one of each. works really well to be honest. I have no compalaints whatsoever, seems to be hard and springy hardened steel. I really torqued down oin them now last christmas while overhauling 2 hubs and no sign of bending or any crap like that, no marks no nothing.

Good and cheap.


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## car bone (Apr 15, 2011)

some nice fantasies about how hardenable steel behaves here I see. lol. Does anyone of you actually read book from time to time??

Grinding down any non cone wrench would do just as fine (probably much much better to be honest), and even the shittiest ones that are useable on regular stuff wuill be more than adequate for this job. You just have to calculate how much time it would take you to do it. and if working that time is better and just buying the crap.

wrenches like this is hardened pretty tough to begin with and they will definitely not go any harder by grinding them. and they will no go significally softer either since that takes a temperature above the tempering temperature for at least one hour. and most likely this is like 200-550C depending on the alloy. unless you get it almost white hot by grinding it, don't worry. Or atleast glowing orange.

Find a belt grinder and use a coarse belt, it has less surface contact area so its much cooler than a fine belt at the same peripheral speed. MUCH cooler. Try 60 or 80 grit, euro or us standard, not japanese.


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## car bone (Apr 15, 2011)

I jusr measured my pedros and they are 2.00 mm so aim for that. I have used them like 10 times and that thickness works.


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## David C (May 25, 2011)

Well I dig trough a old box of mixed wrench and found a few double ended ones that looked decent enough for my needs. Using a belt grinder and my fun, I turned this one (13mm) into a viable tool for my hubs  I should measure the thickness just for reference, but it fits good on a 13mm cone under a locknut on a standard QR front wheel. I have also another 17-14 wrench similar (like already flat) that I'll grind too. I the used a little buffer time to make 'em shiny 

Didn't took long tho.

Pics from my phone.


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## Guest (Jan 26, 2013)

^ dems purdy


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## David C (May 25, 2011)

ahah, I have too much spare time :lol:

Gonna go make the next one now.


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## Guest (Jan 26, 2013)

David C said:


> ahah, I have too much spare time :lol:
> 
> Gonna go make the next one now.


i've done the same with the same


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## One Pivot (Nov 20, 2009)

My park cone wrenches look like crappy cheap stamped steel. They're certainly nothing I would call quality... I bet a ground up harbor freight wrench is stiffer!


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## car bone (Apr 15, 2011)

One P ! they most likely are stamped steel! Myh pedros are too, but they do the job, and seriously how many hubs are you really taking apart/year for me its like 2 or 4. so even if its **** it works.


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## David C (May 25, 2011)

Spent quite a fair amount of time grinding down the second one. Did one side and about half the other one and it took at least twice the time the first one did.

I don't know if it's some harder steel, but anyhow I think it's gonna be worth it in the end.









Is the DIN 894 stamping relate to either steel grade or manufacturing norms ?

The first one was stamped DIN 895 btw.

I'll post more pics tomorrow.


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## David C (May 25, 2011)

Edit. Pic didn't seemed to have loaded properly, and tapatalk won't let me upload to forum again when I edit a post, so here we go a second time :


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## Bro (Dec 20, 2010)

David, how much are seeing that you have to grind from the wrenches to make them usable as cone wrenches? Looking at my Park cone wrenches vs my regular open-end wrenches, it looks like ~1.5 mm vs 5 mm. Is that about the same numbers for you too?


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## Harvie (Jan 27, 2013)

good source for "grindable wrenches " are pawn shops. They will sell the crapsman/china specials for a buck each in this area. Parks are only about 5.50 each though.


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## David C (May 25, 2011)

Eric, I did measure both the 13 and 17mm wrenches I grinded and they pretty much both started at 5mm thick, then I got the 13mm down to 2.5 at the tip and 3 at the bottom of the opening. For the 17mm one, it's a tad under 3mm at the tips and 3.5mm at the bottom of the opening. They look pretty good IMO.

From having used genuine Park Tool cone wrenches, i must say I found them quite thin and often had they snag crossway or trouble keeping them flat and parallel to the axle. Too thin for my taste, but I presume there must be situations where you really need the flatness of those and for clearance issues. I can't imagine them making a tool that won't fit all of the cones and locknuts clearance combinations. That would be a major bummer to see that your pristine Park Tool cone wrench is 0.5mm too thick to get the job done. At least shops wouldn't like that at all.

For my use, I think I'll be just fine. If not, the grinder is just a few feet away from the bike repair area 

Still have to get the 14 and 15 done.

The 17mm one :


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## rdtindsm (Feb 14, 2013)

Just googled the DIN number, DIN is a German standards organization. The web site referenced ANSI and ISO as similar organizations.

So 894 references a whole set of requirements for a particular application. I found a web site that could have provided the standard, but looked like they were selling and I wasn't that curious.


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## bikeabuser (Aug 12, 2012)

My dad made me a cone wrench about 40 years ago using this method ... Don't loose them ... They'll probably last longer than your bike.


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## David C (May 25, 2011)

Just did the 15mm one off a two sided 14/15mm wrench. Too busy to take pics, so I'll finish the 14mm side and then post them.


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## kb4mdz (Oct 22, 2014)

Just found this thread & forum, cuz I'm trying to do something similar; 

I want to take a 15/16" x 1" combination open end wrench, and grind it down thinner, like a cone wrench. I've started with just a standard wrench, slowly, but how do I get a nice polish look on it?

Thanks, 
Chuk


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## David C (May 25, 2011)

For mine, I simply finish with a smoother grain sand paper and use a buffer wheel (on a bench grinder) and polishing compound for hard steel. However, some of the wrench rusted as soon as you took away the nickel plating and some didn't, I guess higher quality wrench have better rust resistant steel alloy than some.


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