Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

pitch of a screw (standard part number)

Status
Not open for further replies.
J

jayanthyk192

Full Member level 3
Joined
Sep 17, 2010
Messages
179
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,298
Activity points
2,580
Hi,

i want a screw of pitch(displacement per degree rotation=distance between thread) 3.5mm or 1.75mm.i went to hardware shops and asked for the same.most of them did'nt know what i was asking.one person showed a screw with 3mm pitch.but it was'nt 3mm it looked lesser,but he told it was 3mm.so would someone please tell the standard part number that i should ask for?the pitch should be 3.5 or 1.75mm.
 

I think you can find different pitch, what exactly do you need, is it a specific pitch?
Are you asking for a screw or a threaded bar (like the ones used with CNC to move the object)?
If it is a screw then I think that the number changes as the diameter gets wider because the slots have to be stronger too (and wider), what size do you use?

14276_242_1.jpg

Alex
 

I have searched for a tap set (used to create threads), the content list had
METRIC set Contains one tap and die in each of the following sizes: 3-0.5mm, 3-0.6mm, 4-0.7mm, 4-0.75mm, 5-0.8mm, 5-0.9mm, 6-0.75mm, 6-1.0mm, 7-0.75mm, 7-1.0mm, 8-1.0mm, 8-1.25mm, 10-1.25mm, 10-1.5mm, 12-1.5mm, 12-1.75mm

so the one that feets your requirement seems to be the 12mm screw (M12) which has a pitch of 1,75mm

Alex
 
I am using it to make a simple xy plotter to drill holes on a pcb.

---------- Post added at 15:47 ---------- Previous post was at 15:44 ----------
alexan_e said:
I have searched for a tap set (used to create threads), the content list had
METRIC set Contains one tap and die in each of the following sizes: 3-0.5mm, 3-0.6mm, 4-0.7mm, 4-0.75mm, 5-0.8mm, 5-0.9mm, 6-0.75mm, 6-1.0mm, 7-0.75mm, 7-1.0mm, 8-1.0mm, 8-1.25mm, 10-1.25mm, 10-1.5mm, 12-1.5mm, 12-1.75mm

so the one that feets your requirement seems to be the 12mm screw (M12) which has a pitch of 1,75mm


Alex
Click to expand...

So M12 named screw has a pitch of 1.75 mm and is 12mm the diameter?
 

Yes 12mm is the diameter, it is called M12

There is a detailed explanation ISO metric screw thread - Wikipedia, the free encyclopedia
There is a table that shows for M12 a pitch 1.75mm (coarse) and 1.5 or 1.25 (fine), I think the coarse versions are the normal ones.

There is also some info Screw thread - Wikipedia, the free encyclopedia

I think you need a threaded bar (or threaded rod), a screw will not be very long (usually)
Take a look at some specifications
You can probably find them cheaper, they are available in many e-stores and even ebay but take a look at the above site to gather some info of what you need.

Alex
 
I saw the tables and the combination you told fits properly. i wanted a little less than 12 mm but its ok. right now I hope to get a 10cm length screw, if I can't then I'll get the threaded rods.
Regarding the name, what exactly should i ask.is it "an M12 screw with 1.75mm pitch"?
 

The M12 is the 12mm diameter screw, if you ask for M12 they will give you the 12mm screw but other than that I doubt that the shop selling them will have any idea of the pitch, they usually don't know such details but the standard pitch for that size is 1.75mm so you will probably get it right anyway.

Alex
 

one more thing: will there be a standard nut that fits on the screw? or is it something like a screw which goes into the body of the equipment being used?
 

this is where you will start having problems, it will be very easy to get a fitting nut for that screw but unfortunately to have accuracy in the movementyou also need a zero backlash nut, usually these are spring loaded custom nuts, expensive and made for specific mating thread.
I have also read of some custom made ones using ABS plastic so that the fit is very precise.

read about backlash at Backlash in Lead Screws: What It is and What to do About It

Maybe you should search or post in a CNC forum to find people specialized in the subject

Alex
 

I haven't forgotten the backlash problem.i actually had thought of using grease to hold it to the screw.but after studying the tutorial I think its a bigger problem. for now i will use the simple parts and later modify it when everything works properly.
 

1.75 mm is a standard coarse metric pitch, as noted above. You may have a hard time finding a long enough cap screw in that diameter. What you should probably ask for is "threaded rod." My American supplier can provide it up to 2m in length (McMaster-Carr).

Since this CNC wil be computer run, I wouldn't worry too much about getting the exact pitch you want. You can take care of almost any pitch in software. As for real cheap anti-backlash nuts, consider Delrin (a.k.a. acetal). It is self lubricating and holds good tolerance. You could tap and drill it yourself, or take two standard nuts in a sleeve and force them together (or apart) with a spring.

John
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top