Apple press screw thread

porkbroth · Post by **porkbroth** » Mon Sep 28, 2020 11:23 am

Hi,

I've got an apple press with a large threaded bar in the middle. To make it faster I wanted to screw a nut down on top with an impact wrench before finishing it off by hand when it needs more power. The problem is I can't identify the thread anywhere so I can't buy a nut for it!

It could be metric or imperial because 19 mm is almost exactly 3/4 inch so I'll state both and hope that someone can help me:

Dia: 19 mm or 3/4 in
Thread pitch: 3.02 mm or 0.1189 in (8.4 tpi)

I measured ten thread pitches and averaged so it should be fairly accurate. As far as I can tell it isn't UNC, ISO coarse or Whitworth so I'm stuck!

Dave54 · Post by **Dave54** » Mon Sep 28, 2020 12:26 pm

How old the machine is and which country it's from might give some idea.
Could well be a thread unique to that maker though. Coarse to give a fast action.
If you have the machinery nothing says you have to make standard threads.

Sorry, but IMHO, if it's not one of the standard threads, you're going to have a job finding a nut. Let alone if it's a "one off" thread.

big-all · Post by **big-all** » Mon Sep 28, 2020 1:32 pm

if you follow the thread round is it a single or multiple thread??
as in mark the thread one rotation and see if you are next to the mark or one away

Bob225 · Post by **Bob225** » Mon Sep 28, 2020 1:39 pm

By the sounds of it, It's an 3/4-8 acme lead screw (flat valley to the pitch)

Nos · Post by **Nos** » Tue Sep 29, 2020 7:02 am

Why do you want it to faster, have you ever pressed apples or grapes? Speed is not the way to go, a slow press with a wait then turn it another once, wait and then keep repeating until you can no longer extract any juice from the pulp, or you could be trying to get in the Guinness book of records for the fastest extractor.

porkbroth · Post by **porkbroth** » Tue Sep 29, 2020 8:38 am

Thanks for all of your replies. It looks like this, except bigger:

: GF7537_Traditional_Fruit_and_Apple_Press_(12_Litre)_with_Straining_Bag%20new-500x500[1].jpg (78.76 KiB) Viewed 4169 times

The thread looks like it could be ACME 29° to me:

: c21e48e6-16ae-401a-9df0-5f6cafabb740.jpg (129.78 KiB) Viewed 4169 times

Bob225, I think you've got it! Thank you very much. It does look like a ACME 3/4 - 8 lead screw

big-all, it is a single thread.

Nos, we've got a few different apple trees that mature from as early as July (Beauty of Bath) to November (no idea what variety) and all in we press about 800 lb of apples every year! We were going to get a bigger press or even a hydro press but because we can rarely get more than 200 lb at a time it doesn't really seem worth it. The scratter is powered by a heavy duty SDS drill. If we can get 80% of the pressing done with the impact wrench before we both heave away on 2' bars then it's worth it to us

porkbroth · Post by **porkbroth** » Tue Sep 29, 2020 11:24 am

Here is a less blurry photo of the screw thread. It might actually be square cut instead of ASME. It's difficult to tell.

: aa399b60-914a-444d-a747-789304259b5f.jpg (191.1 KiB) Viewed 4157 times

Razor · Post by **Razor** » Tue Sep 29, 2020 6:31 pm

Acme threads are square cut. They're the ones you find used as lead screws on lathes etc because they can take very heavy pressure

Can you get a larger nut and have it welded to the end?

porkbroth · Post by **porkbroth** » Wed Sep 30, 2020 7:12 am

The nut has to screw down the fixed thread, rather than the other way around. I had planned to weld about 8" of tubular steel onto the nut and a socket onto the top of that. Does that seem like a reasonable idea?