m5 x 0.8 cap screw stronger than grade 12.9

[Guest]

I need a source for these for my work - as a hinge pin for a pneumatic cutter (like a big pair of tin snips that cuts plastic).

I have talked to McMaster Carr and MSC already.

Who knows a source ?

[Dogma]

You might try a fastener specialist like Fuller, Maryland Metrics, or Metric & Multistandard Components.

12.9 is already mighty tough. If I remember correctly, the last time I needed something stronger, we ended up with a custom part in S7, and it wasn't a screw anymore. For a hinge pin, you might end up with O1, or redesigning for a pivot pin from Misumi.

[GregT]

A possible improvement without reworking the whole shebang would be a capscrew with an enlarged shank retaining a 5mm thread on the end.
Some careful reaming and the load capacity can be increased markedly.

[mriddle]

Thanks for these tips -- learned since this that the hole for this is about M5 but the thread is not relevant. So anything that is the right diameter will work. Grade 12.9 shears in about a day of use.

There is room on either end for some other method of fastening so a pin or dowel would work if it would not shear.

[daturat100r]

Std cap screws are 8.8 but higher grades up to 12.9 are commonly available from good engineering fastener suppliers

[mriddle]

Std cap screws are 8.8 but higher grades up to 12.9 are commonly available from good engineering fastener suppliers

Thanks daturat100r

12.9 grade we have tried many times -- they last an average of a day in service. Need something with that diameter but incredible shear resistance.

As far as boring the hole out to gain strength, there are approximately 50 machines in service with this pin so that would be a last resort for us - but still a possibility.

[Billy Ricks]

Any chance any of these dowels or pins might work? They are supposedly shear proof. .196 works out to about 5mm.

[7981GS]

Have you spoken to the manufacturer of these cutters about the cure?
Certainly, they KNOW of a solution.


Eric

[mriddle]

Have you spoken to the manufacturer of these cutters about the cure?
Certainly, they KNOW of a solution.


Eric

Yes - they want for me to pay them $35 each for this little bolt (similar to an m5 cap screw with a nylon locknut). Original price was $42 each.

The kit that we buy only cost $50-60.

Seems a really high price - for just the tiny bolt.

They will not divulge another source to purchase the bolt.

Suppose I wouldn't either.

[mriddle]

Any chance any of these dowels or pins might work? They are supposedly shear proof. .196 works out to about 5mm.

Thanks Billy

I will forward this to those who know the tech side of things.

[7981GS]

So the loss in production, down time and man hours replacing the bolts daily is more cost effective?
Just how inexpensive are these parts that you make?

Eric

[Nessism]

12.9 grade screws are pretty strong - 175 ksi (stronger than SAE grade 8). You are up into the specialty hardware zone above this level.

Maybe give ARP a ring... http://arp-bolts.com/ They have some special application alloys that go up to 220 ksi. You might get lucky and find some bolts the proper size you need, but they won't be cheap.

[mriddle]

So the loss in production, down time and man hours replacing the bolts daily is more cost effective?
Just how inexpensive are these parts that you make?

Eric

Of course not - but as Materials Manager (not much tech background), I am looking for the least expensive replacement that will do the job well.

I have in the past found $10 bolts (from a purchased assembly) for a little as 70 cents (just from memory).

We have about 50 units in place right now and the only time I need a replacement is if the repair person actually misplaces the bolt when changing out dull blades. I just need spares for that event and would like to find a source where I could buy a carton of 100 bolts one time and not have to worry again for a long time.

Appreciate all the help so far.