Carbide tips

Home Model Engine Machinist Forum

Help Support Home Model Engine Machinist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Herbiev

Well-Known Member
Joined
Jan 6, 2011
Messages
2,360
Reaction score
310
Hi all. I have a couple of face milling cutters and the carbide tips are chipped/broken. Where is a good place to buy new blank tips and what is the best way to weld them on. If silver soldering the tips do I need 45% silver or will the plumbers grade silver solder be ok?
 
Hi all. I have a couple of face milling cutters and the carbide tips are chipped/broken. Where is a good place to buy new blank tips and what is the best way to weld them on. If silver soldering the tips do I need 45% silver or will the plumbers grade silver solder be ok?

Silver solder != silver braze. When a lot of folks say "silver solder" they mean "silver braze", the difference being the temperature - a silver bearing solder (usually tin/antimony with some small % of silver) is applied below a red heat and a silver braze has to be applied at or above a red heat.

In you case you will definitely need the silver braze. You might have trouble removing the original carbides and will definitely want to tin the new ones before application. The flux for carbide is not the regular white stuff but a grey/black flux but other than color I don't recall the difference.

You will also need some way of grinding the new carbide on the cutter.

All in all I've found it easier to simply buy a cutter with replaceable inserts on eBay and have retired the few cutters with brazed points.
 
Hi,

Forget silver solder or the soft plumming stuff unless you are looking for disaster. What you want is silver brazing and this takes a lot of heat to make the paste fuse itself in to the metal, it is a metallurgical process . There are some silver brazing stuff that you could get that come in a syringe, these are already loaded with the proper flux so you'd just apply the paste and heat up fast but these are expensive and they have a limited shelf life.
Personally I don't think it is worth the effort or the money brazing carbide bits but it is up to you.

Regards,

A.G
 
Herbiev
Just to clarify the types of solder to avoid confusion over soft and hard solders:
1. Soft solder, this is the stuff used in electronics and in plumbing. Different compositions are available and can be melted with a soldering iron but in plumbing and some model engineering work a torch might be needed to get bulky items up to temperature. Although it is silver in appearance it is NOT silver solder)
2. In the UK we have silver solder. This is known as silver brazing in the US (not sure what it is called in Aus?). This is a hard solder and needs the work bringing up to red heat or there a bouts so a torch using something like Propane is needed. Again there are different compositions with a range of melting points flow characteristics etc.
3. Brazing is the next on the scale and needs much higher temperatures. To braze you generally need a gas that will provide more heat than Propane for can provide.
Hope that helps .

John
 
Brazing carbide plates used copper wire, flux is a borax or mixture of borax and calcium carbonate. Preheat temperature is about 750-850 degrees Celsius, just needs a soldering temperature of 1100 degrees Celsius.
Instead of the oven, you can try to use an acetylene torch - used in reducing flame zone - requires a lot of practice.
You can even use the warm-up pin - then use the brass.
You can also use induction heating.

I'm thinking that mastering this could be very interesting - but totally unprofitable

Robert
 
Thanks everyone. It seems like I'm in for a newer type of cutter that uses indexable tips. Many thanks for the feedback.
 

Latest posts

Back
Top