Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
(OP)
How do I make sure that both parts are going to fit properly (loosely)? The call out for the insulator thread is: M4 x 0.7 - 6g. The assembler has to re-tap every single aluminium plate to be able to fit both parts.
The call-out for the threaded hole is : M4 x 0.7 - 6H.
Is there a way to indicate in the drawing to make the threaded hole to its maximum major and minor diameters?
Thanks..
JJAV
The call-out for the threaded hole is : M4 x 0.7 - 6H.
Is there a way to indicate in the drawing to make the threaded hole to its maximum major and minor diameters?
Thanks..
JJAV





RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
The Pitch Diameter of the internally threaded hole must be between 3.545mm and 3.663mm. The pitch diameter of the externally threaded component must be between 3.433mm and 3.523mm. You can see by the spec that if the PD of the threaded hole was at its smallest (3.545mm) and the PD of the threaded shaft was at its largest (3.523mm) the parts would still assemble.
Your problem is not in the specification. This is a manufacturing issue not a specification issue. Either the PD of the internal hole is out of spec or someone is chamfering the hole after it has been tapped and is rolling the first thread over, making it difficult to get a threaded part started into the hole. Both of these issues are fixed by chasing the hole with another tap so you'll have to figure out which one it is. Chamfering the hole before tapping solves the second issue I mentioned.
Powerhound, GDTP S-0731
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RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
JJAV
RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
Powerhound, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
MJ; good question. Generally anodized aluminum is tapped before anodizing, and the tapped holes plugged before anodizing. The holes are considered exempt from the anodizing because they aren't exposed after assembly.
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
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RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
Chris
SolidWorks 11
ctopher's home
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RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
MN, you don’t have to be impressed with the gauges, you just use them. You have more choices when measuring external thread, but internal M4 – probably not much.
If thread was machined improperly as PH suggested, the gauge could catch it.
The dimensions/tolerances usually apply for final state of the part, e.g. after coating/plating. It is not uncommon to specify tolerances before and/or after if necessary.
OP seems to automatically put the blame on design, which unfortunately is also not uncommon. In my opinion if both tolerances (6g for the bolt, 6H for the nut) were clearly specified on the drawings, there is no need for any additional “magic” indication.
RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
MechNorth: regarding what you were saying about plugging the tapped holes before anodizing, Is this something the machinist should know or should you put a note to make it clear?
JJAV
INVENTOR 2013
RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
Powerhound, GDTP S-0731
Engineering Technician
Inventor 2013
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SSG, U.S. Army
Taji, Iraq OIF II
RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
Something like "THREADED HOLES SHALL BE FREE OF ANODIZE" should do it. Note - you're telling them the holes are not to be anodized but you probably don't care if they make holes first and then mask during anodize or if they anodize the part and then tap it - so don't tie their hands by saying 'MASK ALL THREADED HOLES BEFORE ANODIZE' as this isn't actually your requirement. I've had vendors come back and ask if they could make the holes after anodize because masking was time consuming or problematic etc.
What's the material of the mating part? Occasionally SST will gall in aluminum. I had some #4-40 holes in 60661-T6 that kept binding on the thumbscrews. Machine shop claimed it was from masking compound left in the holes after anodize but I was never convinced as when I ran a hex head screw through the hole as a crude tap I only ever saw aluminum chips - no 'gunk' or similar.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
JJAV, a good process planning/manufacturing engineering group will include it in their process plans, but to be safe, it is best to put it on the drawings.
Powerhound, SST in alum is a notoriously bad idea, particularly at small thread sizes. Galling, tear-out and galvanic corrosion pathways.
Kenat, in my experience, tapping after anodizing frequently caused localized surface damage to the surrounding anodizing in proximity to the hole. Don't know if that's always the case, but it was on our parts which were milled, tapped, threaded, turned in alu plate, tube, bar and occasionally castings too. Strangely enough, each colour of anodizing behaved slightly differently.
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com
RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
As a sidebar, I haven't had the foul luck with forming taps that you guys have had. I use them frequently in aluminum and especially with smaller sizes since they are beefier than cutting taps. I don't even remember the last time I broke one that I didn't just plain screw up and either try to tap deeper than the hole or get the feed and RPM messed up somehow.
Powerhound, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
You wrote that the tapped holes are not anodized.
What exactly is the issue, do the threaded parts not fit the tapped holes? Or are they too loose? Or ...?
Chris
SolidWorks 11
ctopher's home
SolidWorks Legion
RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
Exactly, the tapped holes are not anodized, the issue is that when the assembler tries to fit both the male polycarbonate M4 part and the aluminum M4 tapped hole, it is just not possible, he has to re-tap every single AL part. So I am thinking that chamfering will really help here as Powerhound suggested.
RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
Chris
SolidWorks 11
ctopher's home
SolidWorks Legion
RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com
RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
Long time no write. It might be that when they retap the threaded holes it gets rid of inconsistencies made during production. By the way I forgot to mention that this problem has been happening on brass material, we have a couple of brass plates that also need to be retapped.
RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com
RE: Male Plastic Polycarbonate M4 insert wont fit in an M4 hole made on an Aluminum plate.
There's no question that re-tapping the holes gets rid of whatever is causing them to fail to begin with because it solves the problem. What you need to do is find out what the problem is. There have been several ideas posted as to what may be causing the problem. Have you followed up on any of them yet? Are you making the plates in-house or is a supplier making them for you? If it's the latter then you need to be communicating with them about this.
Powerhound, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II