Help With Screw Size Please...

[Derek Arita]

I need some cap head screws for my Festool MFT 1080. Parts calls for M8x14-8.8. I'm looking for a source other then Festool, but I'm not sure how to interpret M8x14-8.8 to do a search. I looked on McMaster Carr, but got confused on the numbers. Help please?

[Jared Sankovich]

M8 14mm long grade 8.8

[Edward Weber]

M8 is the shaft size
14 is the thread pitch
8.8 is the length

Are you looking for hex head or socket head cap screws?

Here is a place that has both, I find it easy to navigate

https://www.albanycountyfasteners.com/Category/Screws_And_Bolts?Per_Page=150&Sort_By=bestsellers&f_diameter=%3Cspan%20style%3Ddisplay%3Anone%3B%3E6 30%3C%2Fspan%3EM8&f_system_of_measurement=Metric

[Derek Arita]

M8 is the shaft size
14 is the thread pitch
8.8 is the length

Are you looking for hex head or socket head cap screws?

Here is a place that has both, I find it easy to navigate

https://www.albanycountyfasteners.com/Category/Screws_And_Bolts?Per_Page=150&Sort_By=bestsellers&f_diameter=%3Cspan%20style%3Ddisplay%3Anone%3B%3E6 30%3C%2Fspan%3EM8&f_system_of_measurement=Metric

Socket head cap screws. I see M8-1.25 x 16M (FT). Is this the M8x14-8.8? See...I'm confused.

[Derek Arita]

Sorry...here was my confusion...the parts list calls for M8x14-8.8, but I just sized the screw and it's M8 1.25 x 14mm long. I was searching for M8 8.8 pitch.

[William Lessenberry]

Sorry...here was my confusion...the parts list calls for M8x14-8.8, but I just sized the screw and it's M8 1.25 x 14mm long. I was searching for M8 8.8 pitch.



8.8 is the strength rating.
M=Metric
8=8mm diameter
14=14mm length
8.8=strength rating Like Grade 5, grade 8 etc. in 'merican fasteners.
Sometimes thread pitch is also specified. Standard 8mm pitch is 1.25, fine pitch is 1.00
BillL

[Edward Weber]

I was getting my metric and Standard intertwined. I apologize
So yes, M8 x 1.25 is a pretty common size, all you need to do is find one with the head you want, 14 mm long with a grade 8.8.
This is just an example, but I believe this is what you're after
https://www.fastenere.com/m8-125-x-14mm-hex-bolts-zinc-plated-steel-class-88-full-thread-quantity-25

[Bill Dufour]

M8 is the shaft size
14 is the thread pitch


14 is way to much for thread lead. It would look like a dirt auger.
8.8 would be a special order custom length, unlikely.
Bill D
More words to make the count

[Bill Dufour]

FYI Metric thread spacing is stated in lead, English in pitch.
Bill D

[Edward Weber]

Yes Bill, I corrected my error.

I also don't have the manual the OP is working from, only what he wrote.
My peanut brain built a half standard and half metric bolt.

[Bill Dufour]

My Harrison metal lathe(1976?) is a interesting mix of English and metric. everything is metric except the native English lead screw is the same metric diameter as the Metric one but the threads are like 4 threads per inch. Same deal for the compound screw. Of course the nuts match that odd ball thread. But only those four pieces.
Bill D

[Greg Quenneville]

It's my primitive understanding that it’s very difficult to cut imperial threads with a metric leadscrew but easy the other way around with a 127 tooth change gear. Also, who doesn’t like working in thousandths of an inch? Its more intuitive than some odd number of microns.

[Jerry Bruette]

FYI Metric thread spacing is stated in lead, English in pitch.
Bill D

On a single start thread aren't lead and pitch the same?

[michael langman]

On a single start thread aren't lead and pitch the same?


Pitch is the distance of one revolution of the thread.

Lead is the distance of the pitch in relation to the number of leads or thread starts in a thread.

[Jerry Bruette]

Pitch is the distance of one revolution of the thread.

Lead is the distance of the pitch in relation to the number of leads or thread starts in a thread.

According to the 23rd edition of Machinery's Handbook, I know it's old but I don't think these definitions have changed. The pitch of a screw thread is the distance from the center of one thread to the center of the next thread. This measurement applies no matter if the thread has a single, double, triple or quadruple thread.

The lead of a screw thread is the distance the nut will move forward on the screw if it is turned around one full revolution. In a single-threaded screw the pitch and lead are equal.

Pitch can be a general term of measurement for various mechanical systems. It can mean the distance from a spot on a chain link to the corresponding spot on the next chain link. It can be the distance from a spot on a gear tooth to the corresponding spot on the next gear tooth. It can also be the circular pitch of a gear or sheave. You could even apply the term pitch to woodworking. If you drilled holes for shelf pins that were 3" apart you could claim that your shelf design used a 3" pitch system.

[michael langman]

What you have said sounds right Jerry. I think I said things that mean the same just in different words.

[Bill Dufour]

TPI is also thread count.
I bet many here misuse TPI and call it pitch.
TPI is easier to measure with a ruler then pitch. Not hard to get a good count on normal size threads in one or even 1/2 inch. Metric needs some math to do that.
Bill D