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PTG pilot bushes

Warrensmith

Plastic
Joined
Oct 14, 2018
Has anyone experienced issues with the quality of PTG pilot bushes?

I recently bought a set and while the external surface is ground smooth the inside looks like a blunt drill was used to make the hole then the high spots remove with 100g sandpaper.
 
Has anyone experienced issues with the quality of PTG pilot bushes?

I recently bought a set and while the external surface is ground smooth the inside looks like a blunt drill was used to make the hole then the high spots remove with 100g sandpaper.

I have found that they are a cut below in overall quality when compared to JGS bushings. Haven't had to reject one, just not as nice overall.
 
I’ve got a bunch of them for HSS and carbide reamers and I never even concerned myself with the ID surface finish. As long as it’s a snug fit on the reamer shank and is concentric, it makes no difference to me.
 
my observation has been that the bush tends to remain stationary in the bore therefore rotation occurs on the bush inside surface so if this is less than perfect you will most likely get poor results

My initial post was not to bag PTG or complain about the less than pretty finish. I was experiencing difficulty using them and elimination of other causes indicated they were the source.
 
I always get oil groove bushings for my carbide reamers. Today I got a new customer reamer that had three flats ground on the OD to allow oil to pass, instead of grooves. At first, I thought that's a great idea. Should allow more coolant by. Then I went to measure the bushing diameter and realized what the flaw in this idea is.

Last thing I do before the machine shoves the reamer in is to check the bore size with a HSS bushing on a Grizzly rod, then measure it and confirm the reamer bushing is no larger than the bore. Measuring a triangle is a bit more challenging than comparing diameters.

I'll have to make sure to clarify I don't want triangle bushings next time I order.
 
my observation has been that the bush tends to remain stationary in the bore therefore rotation occurs on the bush inside surface so if this is less than perfect you will most likely get poor results

My initial post was not to bag PTG or complain about the less than pretty finish. I was experiencing difficulty using them and elimination of other causes indicated they were the source.

Thought I replied to this earlier. Why in the World would you have a bushing that would do that. You picked a bushing that is too tight. Personally the way I chamber, I do not want a bushing to affect the travel of my reamer. Think about it.
 
You are reading into my words things i didnt say and things i didnt mean.

None of the bushes i used were tight enough in the bore to stop rotation. There is also clearance on the inside of the bush to what ever it is mounted. It has just been my observation that for what ever reason rotation seems to occur between tool (reamer, grizzly etc) and bush not bush and bore.
 
You are reading into my words things i didnt say and things i didnt mean.

None of the bushes i used were tight enough in the bore to stop rotation. There is also clearance on the inside of the bush to what ever it is mounted. It has just been my observation that for what ever reason rotation seems to occur between tool (reamer, grizzly etc) and bush not bush and bore.

My point on bushings are they have at least .0002 clearance to the reamer and another .0002 from the OD of the bore to the bushing. If your bore wanders a little, so does your reamer. If you reach in the bore to the area that is where your throat happens to be and use a short stiff carbide boring bar and with a loose or no bushing, your chamber will be the most coaxial to your bore. That is why I taper bore toward my indicated throat. This is a good machine shop method to get a true chamber. I found in the olden days that a fitted bushing to the bore with a wandering barrel makes a larger chamber at the base of the chamber.
 
And the bushing rides on rifling. Depending on the number and width of the lands, what is the risk of the bushing deforming the lands? With the bushing guiding the reamer, once the reamer has established the cut but then the bore veers what happens? The bushing must put considerable pressure on the rifling especially if the reamer cuts a chamber larger than the reamer.
 
And the bushing rides on rifling. Depending on the number and width of the lands, what is the risk of the bushing deforming the lands? With the bushing guiding the reamer, once the reamer has established the cut but then the bore veers what happens? The bushing must put considerable pressure on the rifling especially if the reamer cuts a chamber larger than the reamer.

If you have chambered a barrel or 10 you will see barrels that are larger at the base than others. Just different machining practice. You probably learned in your machine schooling that a reamer or drill will follow an existing hole. If you taper bore to an indicated throat your chamber reamer will follow the taper bored hole and be coaxial to the throat. I do not want a bushing guiding my reamer.
I do agree that the cat can be skinned several different ways. I came to my method after many years tweaking my methods. It is not as fast as other methods and I can sure learn from others.
 
And the bushing rides on rifling. Depending on the number and width of the lands, what is the risk of the bushing deforming the lands? With the bushing guiding the reamer, once the reamer has established the cut but then the bore veers what happens? The bushing must put considerable pressure on the rifling especially if the reamer cuts a chamber larger than the reamer.

Just to clarify my point against bushings, if a tight fitting bushing is causing the reamer to cut a large chamber due to a crooked bore (see post no.8) then there must be considerable pressure put on the rifling by the bushing, possibly damaging it or what am I missing?
If the bushing is loose enough to avoid this then what good is it doing?
 
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