Shaft Extension for Door Latch

[Don52]

My customer made a custom door, which was considerably thicker than a standard door. This meant that standard door knob hardware would be too short to reach through the door. Door knob extension kits are available, but these were also too short. To solve the problem my customer purchased a second door knob assembly so that he could scavenge the two shaft parts that were required. The task was to weld an extension to the outer piece that looked like half of a pipe. The inner piece appeared to be made of pot metal and I was reluctant to attempt to weld it. I know that Muggy Weld makes a Super Alloy 1 product that can weld pot metal, but a kit costs $105. My customer and I decided to machine a sleeve to extend the shaft, which would be glued on using Loctite 680. The first picture shows the drawing and the parts that my customer provided.

1. Drawing and parts

I was concerned that the sleeve would interfere with the numbs on the ID of the shaft so I ground them off.

2. Grinding off nubs

I like to remove the plating before I machine plated metal to avoid smearing the plating on the area to be welded, because the plating will cause porosity in the welds.

3. Etch off plating in HCL

4. Plating removed

The first machining task was to remove the radius on the end of the shaft in preparation for welding.

5. Squaring off one end

[Don52]

Next, I trimmed the end of the outer extension shaft.

6. Trimming off the other end

Below are the machining tasks that were performed on the inner shaft.

7. Facing end

8. Center drilling

9. Turning OD

10. Nice coil chip

[Don52]

Here are some additional tasks for the inner shaft.

11. Parting shaft

12. Drilling shaft

13. Reaming shaft

Next, I sanded off the mill scale in preparation for welding.

14. Grinding off mill scale

Now I was finally ready for welding.

15. Setup for welding

[Don52]

Now the welding steps:

16. Ready to tack weld corner

17. Welded out

18. Close up of weld

I didn’t want to penetrate on the inside, because it would interfere with the inner shaft.

19. Inside of weld

The next step was assembling the inner shaft with 680 Loctite.

20. Sleeve Loctited

[Don52]

Here is the painted shaft.

21. All done and painted

And here is the whole latch assembled.

22. All done and painted

-Don

[tarry99]

Wow.....very nice..

[Bls repair]

Very nice , you have a a lot more patience then I have

[Chris401]

Very tedious craftsmanship. Thank's for posting.

[Aeronca41]

Beautiful reults, and really great pictures, as usual! You do nice work, Don.

[ryanjones2150]

It is now the most expensive door knob on the planet! And one of kind!!

[Don52]

It is now the most expensive door knob on the planet! And one of kind!!

Here is what my friend and customer had to say:

“Thanks Don! I showed the entire process to Wendy and Carolyn just now during dinner. Our shed door latch is famous!
One question, why did your customer make such a thick door? Answer: because he could!”

-Don

[Chris401]

Welding on one side, how did you keep the outer shaft from curling up?

[Don52]

Welding on one side, how did you keep the outer shaft from curling up?

On picture #16, you can see the aluminum bar that I clamped it to, which helped keep it straight. Also I tack welded both ends before I welded it out.

-Don

[Chris401]

I see it now.