Pump pushers vs flat pushers vs concave pushers

[ifibrin]

I was wondering about the different pushers used in a jeweling tool. Seitz makes pump pushers, flat pushers, and concave pushers. I understand that pump pushers allow the jewel to be centered when pushed into the hole of the mainplate/bridge, while concave pushers allow curved jewels (usually endstones) to be pushed without risk of the jewel breaking.

Is there any advantage to using a flat pusher over a concave pusher when pushing a flat jewel in? In other words, can you use a concave pusher to push flat jewels in? Is there some issue with surface area when using a concave pusher to push a flat jewel? For some reason, Seitz/Bergeon concave pushers are much cheaper than their flat pushers.

[Randy55]

I think that just the fact that a flat pusher "pushing" on a flat surface has "mechanical merit" vs. using a concave pusher on a flat surface.

More even contact across the face of the jewel...less chance of damage

 

Just my thoughts.

 

Randy

[nickelsilver]

I think Randy hit it on the head. More contact is a good thing. The advantage of a concave over a flat pump pusher for convex jewels is the contact is near the edge, where with a flat it would be at whatever diameter the pump piece comes out of. I do use flat pushers frequently for convex jewels though, and it hasn't been an issue.

[ifibrin]

17 hours ago, nickelsilver said:

I think Randy hit it on the head. More contact is a good thing. The advantage of a concave over a flat pump pusher for convex jewels is the contact is near the edge, where with a flat it would be at whatever diameter the pump piece comes out of. I do use flat pushers frequently for convex jewels though, and it hasn't been an issue.

Aren’t most convex jewels in shock settings for balance wheels these days? And if the convex jewels aren’t in shock settings then they are rubbed in?
 

Anyway it’s kind of odd that the concave pushers are more expensive than the flat ones… you would have though it would be more expensive to make a flat pusher!