Screws for Hubbard plastic jacks

Dear members,

Any idea where I can purchase screws which fit the Hubbard plastic jacks?
By preference via a retailer in Europe but all other addresses are welcome.



Hubbard jacks have two screws, top and bottom. Which are you looking
for, and how many do you need?

Le 11/02/2024 13:55, Chris Vandekerkhove via The Jackrail écrit :

Three: some Hubbard jack models have also a screw for a “regulable” damper holder.

From memory they would be standard screws freely available, nothing special about them. But for sure, coming from America, the thread would be UNC or UNF or one of the other American series. So you’d be better off searching for an American supplier of industrial screws like this. Here’s a good page about UNC and related threads:

You should be able to measure the size and figure it out.

No doubt our American members will know good industrial screw supply sources.

If you just need a handful, I have a few spares and could sent you some.
I am surprised, though: my instrument has been in use for 49 years now and I never had to replace a single screw . . . :thinking:

Not the type of screws you find everywhere: the heads were not of any of the common type. They had a slot, but a philips would to. But the profile was uncommon. They were not flat, they were not semi-spherical: their profile was similar to the brass wooden screws with round head, but the head was flatter, and it did not have the edge. Let me see if I have a picture somewhere …
No, I made-up one with the correct proportions. About 15mm long.

| andro Andrew Bernard
February 11 |

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American screw thread gauges

American inch-based screw thread series, used in bolts, machine screws, threaded holes in castings, and so forth. Threads per inch, diameters of clearance holes, size of tap drills, and size of nuts.

You should be able to measure the size and figure it out. My 1973 Kit instructions list them as

Jack top: 2-56x1/4" slotted stainless set screw, cup point
Jack bottom: 2-56x5/8” binding head machine screw, stainless


The damper adjusting screw is a #1 x 1/8" long, pan head slotted screw. #1 screws come in two pitches, 64 (UNC) and 72 (UNF) tpi. I do not have a gauge to determine which it is, but the other two are UNC , so the odds are that this one is, too. In addition to McMaster-Carr, there are, ,, and You also might check for local suppliers of model railroad supplies. Those here in the US often offer both imperial and metric sized hardware.

I will mention that McMaster-Carr will not sell to individuals, only to businesses, in my experience. I am in Canada (not the US) so perhaps they sell to private individuals domestically, but certainly not internationally. But when I amended my order to include my business credentials, it went through without further difficulties.

They may be truss-headed screws. I see in my local fastener supplier’s catalogue that there is such an item, flatter than a normal round-headed screw, yet not totally flat.

The head diameter of a truss-headed screw is distinctly larger than a round-head screw, based on the reference charts at the back of the catalogue.

Thank you for this information. I was looking for the bottom screws “Jack bottom: 2-56x5/8” binding head machine screw, stainless”.

If I got it correctly, then these are the type of screws to order from McMaster-CARR:

5/8" Fully Threaded __ 0.181" 0.050" 100,000 ASME B18.6.3 100 91793A083 6.39

Can someone confirm please?

Thanks in advance,


Hi Chris.

For my 3D printed Hubbard jacks I’m using these:

Based on the catalog number, they should be the same thread size and pitch as the model you indicated, only 3/4" long instead of 5/8". So, if your Hubbard jacks are original, I’d say that the model you picked should be the correct one. I can’t remember if the original jacks can accommodate the extra length (the additional steel helps my 3D printed jacks to weigh practically just like the original ones).