Question about thread pitch

[JBW]

I have a Buck 8" 4 jaw independent chuck that I need to put a back plate on. The Buck company said I need a M10 socket head bolt, but I don't know what thread pitch to use. The options I have is a M10 X 1.0 or 1.25 or 1.50. What thread pitch would be best or does it make any difference? The back plate that I will be using will have to be tapped. Obviously I an very new to machining.

Thanks for any help you can provide.

 

[Bob Korves]

Standard 10mm bolts have 1.5mm threads. I would expect that to be the ones used, but you never know. Count the number of threads in 9mm of threading to confirm. Only the correct pitch will screw into an existing thread.

 

[Alexander McGilton]

I would go for 3/8-16 as it's just slightly smaller it will fit the counter bore of the chuck. If you are drill and tapping the back plate for the chuck then it's up to you.

Just to confirm we are all on the same page, you are trying to determine what screws to you in this situation?

 

[petertha]

Before you go down that path, you might want to see if a back plate is available for the bolt pattern/configuration of your chuck & spindle. Fully machined costs more, but then you are home free, just get the bolts which match the tapped holes. There are some Asian chuck accessories out there that are reasonably priced compared to a lump of steel or cast iron. If its semi machined then typically you mount the plate to the spindle, machine it true & turn the boss for whatever kind of recess you have on the chuck back face. Then yes, you must drill & tap to your chuck to match.

pictorial examples
https://www.shars.com/products/work...dapter-back-plates?spindle_nose_type=D+Series

 

[middle.road]

A quick perusal of Buck's catalog shows all their chucks using M10x1.5mm as Bob mentions above.
http://shopbuckchuck.com/assets/docs/1503.pdf

 

[MrWhoopee]

This brings up a common source of confusion for those of us raised with UNC and UNF. In the metric thread system there is only ONE standard pitch for each diameter. It is specified as Md where d is the diameter. All others (generally finer than standard) are specified as Md x p, where p is the pitch. The standards, for the most commonly encountered sizes, are M4=.7, M5=.8, M6=1.00, M8=1.25, M10=1.5, M12=1.75. The standard metric sizes seem to be somewhere between UNC and UNF in coarseness. Put a 5/16-24, 5/16-18 and M8 bolts side by side and you'll see what I mean.

 

[Suzuki4evr]

10x1,5

 

[BtoVin83]

I would disagree on only one thread pitch per size, from the Engineering Toolbox;

There are three kinds of ISO metric threads:

• coarse
• fine
• extra fine

 

[Bob Korves]

https://en.wikipedia.org/wiki/ISO_metric_screw_thread
"The “coarse” pitch is the commonly used default pitch for a given diameter. In addition, one or two smaller “fine” pitches are defined, for use in applications where the height of the normal “coarse” pitch would be unsuitable (e.g., threads in thin-walled pipes). The terms “coarse” and “fine” have (in this context) no relation to the manufacturing quality of the thread.

In addition to coarse and fine threads, there is another division of extra fine, or “superfine” threads, with a very fine pitch thread. Superfine pitch metric threads are occasionally used in automotive components, such as suspension struts, and are commonly used in the aviation manufacturing industry. This is because extra fine threads are more resistant to coming loose from vibrations.[6]"

International

• ISO 68-1: ISO general purpose screw threads — Basic profile — Metric screw threads.
• ISO 261: ISO general purpose metric screw threads — General plan.
• ISO 262: ISO general purpose metric screw threads — Selected sizes for screws, bolts and nuts.
• ISO 965: ISO general purpose metric screw threads — Tolerances[7]
  • ISO 965-1: Principles and basic data
  • ISO 965-2: Limits of sizes for general purpose external and internal screw threads.
  • ISO 965-3: Deviations for constructional screw threads
  • ISO 965-4: Limits of sizes for hot-dip galvanized external screw threads to mate with internal screw threads tapped with tolerance position H or G after galvanizing
  • ISO 965-5: Limits of sizes for internal screw threads to mate with hot-dip galvanized external screw threads with maximum size of tolerance position h before galvanizing

National

• BS 3643: ISO metric screw threads
• ANSI/ASME B1.13M: Metric Screw Threads: M Profile
• ANSI/ASME B4.2-1978 (R2009): Preferred Metric Limits and Fits
• DIN 13-1

 

[MrWhoopee]

I would disagree on only one thread pitch per size, from the Engineering Toolbox;

There are three kinds of ISO metric threads:

• coarse
• fine
• extra fine

I stated that there was one STANDARD diameter/pitch combination, which is designated as M8, M10, etc. All others are specified with diameter and pitch (M8x1.0, M10x.1.25). In the link Bob posted above, it is referred to as Preferred.