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woodworking tool fix with machinists tools

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Blog entry by hobby1 posted 09-02-2013 12:16 AM 912 reads 1 time favorited 6 comments Add to Favorites Watch

Hello,

This is a build blog for fabricating a new combination square clamp, it is that part of the square that gets bent and finally breaks after normal usage, usually the pin breaks, this is because the whole square is built rigidly with a cast aluminum body, and a stainless steel blade, beautiful small 6” squares to work with, but the clamping mechanism is cast aluminum too, and always wants to bend and break at its pin location.

The first one broke, I went to town bought a new one, but when this one broke as quick, I knew I had to make the clamps out of steel.

One of my hobbies besides electronics, is home shop machining, I love to design and build mechanical projects, with my harbor freight benchtop machine tools.

I have the run of the mill hobbyists version of a 7×10 mini lathe, and micromill drill.

Because of this hobby I have the means too fabricate and fix my woodworking tools as well.
I already made a 1MT arbor for the headstock on my wood lathe to turn small wooden wheel handles for my miniature table top wishing wells.

Now I need to use my hobby machining skills to make another fix for another woodworking tool.

So here is a quick build blog on how I built new ,combo square, clamps.

The square at the top left has been fixed with a new clamp and is completed, it works fine, but because both squares have different manufacturers, I need to fabricate the second square clamp, from new measurements, as one square differs from the other in widths of the clamp.

Here is the original clamp piece from one of these squares, it has the guide pin broken off, I’m not using this as a template for the new builds, rather I’m going to set this aside, and fabricate new ones using the square parts themselves, and do emperical measurements and calculations, to get the best fit possible.

so I cut off about 1-1/2” length of 3/8” drill rod.

step one is to turn down the dia. to around 0.250”, for a length of around 0.400”

Then using a die, thread it to 1/4-20.

Here is the resulting piece ready for the milling process.

Now comes the fun part of machining parts, I need to first secure the dimensions of the opening this piece will fit into, it turns out to be around 0.270” square.

So now I have the workpiece in my spin jig, so I can maching all four sides easily, to make a square around 0.260” the 10thou. less is for some clearance, in the hole.

Now after doing some additional measurements and a lot of basic math, I was able to determine the amount of material to take off,for the beginning of this next procedure.
The material left over, is the clearance thickness of the clamp in its hole, to the top of the blade, plus the depth of the slot in the middle of the blade.

Now securing the last dimensions, is to determine the half blade width to the edge of the pin, plus the pin width, and finally the pin depth, which this depth turns out to be around 0.035”

with all this determined, I machined a pin 0.080” wide by 0.035” high and situated the edge of the pin 0.355” from one end of the clamp so the blade can nestle into the pin, and the clamp can slide properly on the blade in its slot.

here is the piece still attached to its parent material.

and the fun math that was involved.

Lastly the pin is machined with square corners, the slot in the blade is a concave half round deal, so the clamp does not fit properly yet,


Therefore some needle file work to shape the pin is in order.

now thats better, it now fits snugly yet loose enough to slide on the blade.

Now I have both squares repaired and working properly again, so with two squares I can have one set for (1/8” and 1/16”) and the other is set for (1/16” and 1/32”).

These clamps are made of steel so I do need to tighten them a little tighter then the original, because steel against steel needs to have more friction then aluminum against steel, but they tighten and loosen very easily and slide properly in there blade slots, and they wont break as easily as the aluminum ones did.

This was a fun woodworking tool fix project, using my hobby machining tools, its fun to use these machines and tools to fabricate and make better parts for woodworking tools.

Have fun in the shop.



6 comments so far

View RobynHoodridge's profile

RobynHoodridge

126 posts in 1052 days


#1 posted 09-02-2013 03:25 AM

I love it. I SO want a mill.
Surely most of the friction keeping the setting is between the blade and aluminium body? So that the steel pin wouldnt change much and you shouldn’t need to tighten more?

-- Never is longer than forever.

View stefang's profile

stefang

13530 posts in 2057 days


#2 posted 09-02-2013 10:06 AM

Great work on these clamps. I have often wished I had some small machining tools and skills. Unfortunately I don’t have any spare room for them in my small shop. There are so many things that could be repaired instead of thrown away. It seems that many if not most tools these days have what I call a weakest link, meaning the tool could last for a lifetime except for one little, but essential cheap part that breaks and a replacement part can’t be found or purchased, like your square clamps.

-- Mike, an American living in Norway.

View Mark Shymanski's profile

Mark Shymanski

5115 posts in 2435 days


#3 posted 09-02-2013 03:34 PM

+1 What Mike said. If you can mill metal and fabricate with wood just about anything is possible!.

-- "Checking for square? What madness is this! The cabinet is square because I will it to be so!" Jeremy Greiner LJ Topic#20953 2011 Feb 2

View hobby1's profile

hobby1

291 posts in 1020 days


#4 posted 09-02-2013 08:23 PM

Robyn—
Your right, it would pull tighter against the square body, however I am using a 1/4-20 nut with smooth facet surfaces, making it harder to grasp onto to twist it tight, if I had a knurled nut like the original, I could probably get a good finger tight grip on it.

If I need to make a better finger tightening gripping nut, I’ll have to do it with my milling machine, because I don’t have any knurling tooling for my lathe, to do it with, however I’ve made plenty of knurled facets on knobs using my mill combined with the indexing jig.

If I do decide to do this, I’ll whet your apetite for a mill, by showing the procedures being done, and I’ll post them in this thread for you, to show another example of what can be done with a milling machine, for the small home hobbyist work.

Mike,
Thanks, these little machines are great assets to have around, if you can find the room for them, the two machines I have can be picked up, and moved around if needed, the lathe is only around 90 lbs, and the mill was around 100 lbs, but now I have a bigger table oin it, so it comes in around 115 lbs. aproximately.
They are great for fabricating those hard to find parts needed to keep apliances, and tools working properly.

Mark,
I agree, +1 what you said, as well.

Guys, have a great day.

View PDuff's profile

PDuff

5 posts in 541 days


#5 posted 10-03-2013 03:29 AM

Nice work on fabing your own part. The bench top multi mill machines are on my list of machines to look into once I get a bigger garage space, though still after some other big pieces for woodworking. Of course, this may change if I stumble upon some good deal on bridgeport with DRO already installed…

For everyone else that breaks these and can’t mill a new one, can’t solder the snapped piece back together, or doesn’t like the idea of “machining” one with a dremel, mcmaster.com sells the starrett replacement ones for around $13. I’m not sure if they’d fit for other brands, but it’s something to investigate. Woodcraft stocks starrett products so you might be able to test and order one through them.

View hobby1's profile

hobby1

291 posts in 1020 days


#6 posted 10-03-2013 02:57 PM

Thankyou for the complement,
also thankyou for sharing the information of where to get replacement parts, that should be of great help for those who need to fix there tools.

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