Help me re-design this please

[mikeyr]

So, I need to make 4 (2 left, 2 right) interior door locks for a old 1934 British car, no keys or anything its just something to open the door. I only have 2 springs, but I don't see why I can't use modern coil springs near the base of the arm to a new post in the lower right. Or is there a better place ? I am a little concerned that the spring would get in the way of the bar that will be at the bottom of the pic. That notch with 2 brass washers at the bottom of the pic, that is for the bar that goes to the exterior door lock/latch at the front of the door and spring will go in same direction.

Then for the other side, I need to figure out to make this part with the square section that goes into the handle itself. I would rather not re-invent the wheel, i even thought of using socket extension cut to fit but wrong size, I do have a small metal lathe and mill combo (shoptask bridgemill), but certainly not a machinist, I could turn it to size, but no idea how to mill that perfect square...only have to make 4 so I could use a hand file I guess. Or buy some type of indexing (expensive) tool for the mill this is GJ after all.


It all looks really simple to make, I would not mind making up more than 4 for others in the club and if i did, i would rather avoid hand filing. I have pretty good drawings of the parts but you get the idea. Basically, can I get away with a modern spring that i can get at any corner store so I am not dependent on that spring that I can't get more of. I can weld it all up where it calls for the pins to be swaged in or do the swaging but wondering if some screws might not be better. Screws would require more machining since I have to tap the parts and welding the posts in is pretty easy. Basically its all covered by upholstery and only the handle will be visible so I am free to do anything as long as I stay with the overall plate size that is inlet into the wood door frame. I am also worried about the angle, I would love to be able to change it after assembly to make the door handle sit at the right angle, but that would require splines above my machining skills, unless I can find something pre-made to cut/weld together.

 

[no704]

Send cut send for the flat parts. Maybe use shoulder bolts.

 

[mikeyr]

well, more research and it looks like a fly cutter will make the square end very easily, cut the first one and then place it against the vice and do the next one, that will be 90 degrees and repeat 2 more times and I have a square, just have to make sure I place the round part of the rod at perfect height each time using a block under it... So now to get a fly cutter, going to do this out of Delrin first try since I have some and then not sure, the original shaft in was brass but if I do steel I can weld it up. This is going to have a learning curve, it looks easy, some would say too easy

 

[rustyzman]

Make the shaft blank (round part) in the lathe, turned, drilled, tapped, etc.
Mount that turned piece in one of these square collet blocks in a 5c collet of appropriate size.

Clamp the square collet block in a mill vise and mill with any appropriate endmill. Set it up against a stop or with a straight edge to the side of the vise jaw (fixed rear jaw) and rotate and repeat. You can get a very nice square, and quite accurate if you are careful. These are very handy blocks to have. With a bridgeport you can tip the head and make it a tapered square if you want it to self wedge/lock too.

https://www.amazon.com/dp/B073B7S7G1/?tag=atomicindus08-20

Those clocksprings were used extensively in window regulators too.

1936-1946 Window Regulator Repair Spring Chevrolet and GMC Pickup and Big Truck

A new window regulator repair spring for the 1936-1946. Holds the window in a raised position so that it does not gradually lower as you drive. A broken side window spring is never good in the winter or if your wife has just had her hair done. Zinc plated. One per door. Sold Each

oldchevytrucks.com

for inspiration as well...
You can mount a tension or compression spring wherever you feel is easiest and will not interfere.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

 

[gahrajmahal]

If you have a scanner at home scan both sides of the latch assembly. As no704 says, send those scans to” send cut send” for laser cut components. Use shoulder bolts or other fasteners. Go to McMaster Carr for inspiration.

 

[alfadan]

Do you mean an endmill instead of flycutter? Flycutting is for light cuts over relatively large flat surfaces.

For this application, simple indexing with a square or 123 block would be fine. Set part against a vice stop, mill a flat, rotate 90⁰ and set with a square, repeat.

 

[mikeyr]

I did mean flycutter, i found a youtube video where that is what they used. It did seem overkill but he was using the endmill on a 3/4" rod and milling a square at one end, looked easy. I will try with my endmill's, i have a 1/2" one that should do the job. I have had this lathe/mill combo for over a decade and only used it to turn stuff, looking forward to being very careful and learning the mill part on what looks like a easy project. I will do it in delrin first time as a test.

 

[Jacko264]

what make of car is it for please
Graham

 

[mikeyr]

1934 Singer Le Mans, old British car and no, the US, the UK and Australia clubs don't have this part

 

[mikeyr]

Well right or wrong it’s done. I bought a fly cutter but ended up doing it with a mill. All 4 done. My first attempt was a miserable failure. It was not square and off by a lot. I milled one side and put it against my vice to do the side and way off. I guess my $4.00 at a garage sale vice is ****. I could see the jaws move as I tightened it. I ended up marking the square and eye balling it and all 4 very nicely

 

[rustyzman]

Good to hear you had success.

Drill press vises don't have the rigidity for the side forces of milling.
Keep your eye out for a proper milling vise, even an import one. A better vise will make your machining ventures much more pleasant.

Glad you found a way to do it.

 

[alfadan]

Yes a milling vise as above and a set of parallels too.