Desmond Stephan 51S screw

[Sawmill7]

I am still looking for screw or measurements of diameter and tpi and pitch. If someone could measure a screw they have I do have someone who will make it for me thanks for any help. Bill

 

[SkyPuncher]

Hi Sawmill7, my old Desmond Stephans 51P was easy enough to get to and I would think the measurements would be the same between the swivel and non-swivel version. Some of this might not be useful to you, but here is what I got. Let me know if I could do something better or you need something else.

Total length of screw with "hockey puck" 19 - 5/8"
Screw up to the "hockey puck" 16 - 3/4"
Length of threaded portion 12 - 1/4"
Diameter 15/16"
TPI 4 threads per inch
Handle length 14 - 1/2"

 

[Sawmill7]

Thank you very much so is there a certain name for the threads..witworth..acme..or something else? Just in case the machinist asks. Only thing I can give him is the nut off the vise. I really appreciate you getting these measurements for me..will post a before and after pic when completed
Thank you. Bill

 

[SkyPuncher]

Well Sawmill, I would say it is Acme thread. Now I have been known to be wrong from time to time and if you are looking for a second opinion, I would try here:

VISE REPAIR 101 all vise repairs, lubricants, sources for parts and the tricks to fix

I'm starting this thread to help me because i'm going to restore quite a few vises and I've only paid to have that done or done some basic repairs so far in my 60 years. as with all tools different manufacturers all do things a bit different and some makers even do different things on their own...

www.garagejournal.com

But per this article:

Screw Thread Types And Their Benefits

Clamp screws come in many forms. There are Standard threads, ACME threads, Buttress threads, and Square threads. Each of these threads may be used in clamps and vises for different reasons.

dimide.com

ACME threads are commonly used in clamps, vises, and linear actuators. The main advantage to an ACME thread is a low number of threads per inch. This allows ACME threads to allow for increased linear actuation per turn of screw which is similar to a square thread. The difference between square threads and ACME threads is the angled root of the ACME thread. The angled root allows for ACME threads to be more easily manufactured compared to the square root of a square thread. The root of an ACME thread is also larger which delivers increased strength in preventing stripping and wear of the thread. It should be noted that the typical controlling failure mechanism of a screw is torsional shear which is based on the minor diameter of a screw and not on the type of thread.




Let me know if you need any other measurements and I'll be happy to help!

 

[RoninB4]

Not wanting to cause trouble here but a quick search on the internet showed no standard Acme thread at 15/16" diameter, they go from 7/8 to 1" in diameter. Furthermore, the TPI for a standard Acme thread of that size is usually 6 TPI. A check in my well worn copy of Machinery's Handbook (20th edition) that shows many variations of thread types doesn't list an Acme thread like that either. The OD isn't all that critical to identify an Acme but the thread form, pitch diameter, and root diameter is important. What is also important is whether the TPI is single start or multiple starts, uncommon but not unheard of. If the OD is 15/16 it might be a metric 24 MM but only if it was not made in the USA and it's an older vise but the Desmond Simplex appears to have been made in R.I.

There are at least 3 types of Acme threads and an untold number of "Modified Acme" in existence. All have slightly different geometry/dimensions. I'm not stating that the OP has a non-standard thread but my references/searches indicate this is likely. Sometimes tooling for items like this were/are non-standard to ensure replacement from the factory and nobody else. Also, some industries (like makers of vises, microscopes, plastic containers, etc. ) use designs that are sorta standard to them and no/few other industries.

To the OP-If you're going to have a new lead screw made by a shop I'd suggest you take them both the lead screw AND the nut. Anything non-standard can be made but a new lead screw and nut may be a simpler (but a bit more expensive) a solution to ensure proper fitment. Post what happens and/or price quoted for this if you don't mind.

 

[Sawmill7]

Thanks for your input. As the picture shows the screw is broken off right at the start of the threads and the threaded part is missing. I can only show machinist the nut.

 

[RTM]

Thank you very much so is there a certain name for the threads..witworth..acme..or something else?

looks square to me, and this catalog cut claims square thread on page 3

Desmond-Stephan Simplex Vises : 1952 Catalog [Part] : Desmond-Stephan Manufacturing Co. : Free Download, Borrow, and Streaming : Internet Archive

3 p., illus., 27.9 cm, trade catalog

archive.org

 

[SkyPuncher]

Looking back at the picture, you guys are right, it does look square and theres the catalog that mentions it. Good eye! I can take a closer look tonight now that I now what to look for. I am far from any kinda expert on the subject and not even that good at taking pictures! Great thing about this forum is the amount of knowledge floating around!

 

[G-ManBart]

Most vintage bench vises I've handled (hundreds) have square threads, not Acme. In many cases they are non-standard. As an example, I just fixed a Parker 975 screw and it was 1.10" and 3TPI square thread...you won't find that in any book. The machinist is going to need the nut to confirm fit since it's likely non-standard and should be able to confirm the thread type. In a worst-case scenario a casting of the nut could be made using Cerrosafe that would unthread and could be measured. Cerrosafe is normally used to make precise castings of gun chambers that are dimensionally accurate after cooling.

 

[Sawmill7]

All this information is very helpful. I would love to restore this vise to be usable. Bill

 

[RoninB4]

As the picture shows the screw is broken off right at the start of the threads and the threaded part is missing. I can only show machinist the nut.

-Yes it's broken off at the start of the thread but there may be enough of the thread form to determine whether it's a square thread or not. Other members here have posted that a square thread is somewhat common for older vises (don't recall mine) so even a broken nub may be enough to gather some information. The experiences of the other members here is more valuable than my experience as just toolmaker.

 

[Sawmill7]

Machinist has parts. Will show finished product and project when they arrive. Bill

 

[Maui]

I am still looking for screw or measurements of diameter and tpi and pitch. If someone could measure a screw they have I do have someone who will make it for me thanks for any help. Bill

Please let us know what this costs you. Some of us have vises with similar issues.

 

[Tober]

Have you ever resolved this?
I also have a 51S vise in very good condition except for the nut, it was swapped out for one from a different vise and it does not fit properly
i would love to get dimensions and pictures of an original one. Or perhaps someone out there has a 51S for sale? I seldom see them

 

[Sawmill7]

Have you ever resolved this?
I also have a 51S vise in very good condition except for the nut, it was swapped out for one from a different vise and it does not fit properly
i would love to get dimensions and pictures of an original one. Or perhaps someone out there has a 51S for sale? I seldom see them

Had a new screw and nut made. Friend is a millwright and ordered a new 3' piece of rod an2 nuts and made it all work.

 

[Tober]

Had a new screw and nut made. Friend is a millwright and ordered a new 3' piece of rod an2 nuts and made it all work.

sooo, would you happen to still have the original nut?

 

[Sawmill7]

No..cut off threaded part and welded and machined two new nuts to match 1".threaded rod and welded it to the tapered part
Works great.

 

[Tober]

Got it thanks,
I may be heading down that same road