It’s not as easy as it sounds. Choosing the right brake lathe cutting tip, that is. There are a few questions you need to ask yourself before you decide on the tip you need.
What grade of tip do I need?
Goodson carries three grades of tips
- Standard Carbide
- Honed Edge Carbide
- Premium Titanium Coated Carbide
The common element here is that all of the cutting tips are carbide. Why carbide? Carbide is used because it holds the cutting edge longer and it will stand up to the wear and tear of daily use. In fact, carbide can hold the cutting edge up to 20 times longer than ordinary tool steel.
Let’s look at each of the grades and see why there are three grades to choose from.
Standard Carbide tips are your basic all-purpose cutting tips. They are parallel ground carbide and are ideal for resurfacing cast iron drums and rotors.
Honed Edge Carbide tips are a step up from the Standard tips. They are both parallel and peripheral ground to give the tips a sharper cutting edge. Honed Edge tips can be used for cast iron and composite rotors and are ideal if there is any rust on the rotor surface. The honed edge will cut through the rust without losing their edge.
Just because these tips can stand up to rust doesn’t mean you can try to turn a rotor that has heavy surface rust. You should still remove as much of the surface rust as you can before you start cutting on the lathe.
Premium Titanium (TiN) Coated Carbide tips are the cream of the crop, the top of the heap. These tips are also parallel and peripheral ground to create a super sharp cutting edge. They are then coated in titanium to help retain the edge and prevent corrosion. Use titanium coated carbide tips when turning cast iron and composite rotors but DO NOT use titanium tips on rusted surfaces.
What shape tip do I need?
Most brake lathe cutting tips are triangular. That has been the standard for many years. Some brake lathes use a parallelogram shape (remember high school geometry?) but that is the exception. A newer shape for brake lathe cutting tips is round. Round tips have been used for years in metalworking and they’ve moved over to automotive work more recently.
Round tips have a few advantages over other shapes, including a smoother cut and more cutting surfaces depending on the cut depth as you can see in the illustrations above right.
What rake should I get?
Brake Lathe Cutting Tips are either positive or negative rake. Whether you need positive or negative rake is determined by your brake lathe design. You can’t use a negative rake tip on a machine designed for positive rake tips without making modifications to the lathe. You may get away with this switch by choosing a different tip holder, but we recommend staying with the rake tip that the manufacturer specifies.
Due to their design, positive rake tips have 3 cutting edges and negative rake tips have 6 cutting edges. For more on rake, see the illustrations at right.
So, which tip do I order?
We’ve covered a lot of ground here, but you may still be asking which tip you should order for your shop. The best way to determine which tip you want is to look at what tip your lathe manufacturer specified. The Goodson catalog and website list most OE tips numbers that correspond to our order numbers so it should be fairly easy to pick out the right tip.
If you don’t have the OE number and aren’t sure which brake lathe model you have (maybe you bought it second hand), you can still figure out which tip you need simply by measuring the height (A), the thickness (B) and the hole (C) size (if there is a hole). You’ll find a chart with all of the tip measurements in the 2013 catalog on page 110 or go to the Brake Tip Measurement Chart on the website. It’s no problem if you don’t have access to either of these charts; just call Goodson at 1-800-533-8010 and give the dimensions to your customer service representative. They’ll be able to convert the sizes to the tip you need in no time.
As always, if you have any questions about choosing a brake lathe cutting tip, contact the Goodson Techxperts™ or visit the technical library on the Goodson website.