A few months back Chris showed some photos of his dissected turret http://www.woodworkforums.com/showth...79#post1810179 I said I wouldn't mind something similar and Peter sent me an early Christmas present.
Thank you Peter.
The turret's arbor is a Jacobs Morse 2 to J6, a bit beefier than Chris's. The indexing mechanism isn't as beefy. It's simply a spring loaded detent pin with a tapered nose locating in a corresponding tapered seat. Corrosion and wear have taken their toll and the pin wobbles*. I made a replacement pin based on the dimensions of the original. The pin is a reasonable fit in the cast iron body but when located in the turret's indexing hole it needs to be pushed in hard to prevent turret movement. I measured the taper angle to be 9.5 degrees and made a series of tapered test cuts on some bar at and close to that angle to check the fit in the tapered hole. I'm thinking a longer nose on the pin might be an improvement.
I thought the turret's appearance would be improved with a bit of wire brushing and maybe a bit a wet and dry. Didn't do much to improve things so I took a light cut off. This is the hardest cast iron I have ever encountered with some areas harder than others.
Five of the the turret's tool mounting holes were bored slightly undersize, about 15.5mm. The remaining hole was exactly 5/8". Given the problems I have had with tailstock alignment I thought I would mount the turret in the headstock spindle and bore out the holes with a boring bar. At the lowest speed the finish was rough so I thought I'd have a go with the turret tailstock mounted. My plan was to use my imperial boring head until I discovered I'd swapped arbors on the thing and it was sporting a 30 taper. My Kaiser boring head came with a screw on 3M arbor but I didn't have a suitable draw bar for its installation in the Hercus so I went on to make two decisions that were my downfall.
I bored the holes with a 5/8 " slot drill only to find they were slightly undersize so I then used a 5/8" reduced shank drill bit mounted in a collet to open the holes up. May as well have been a licorice twist.
With a length of precision ground 4140 as a test bar, there is up to 15 thou (0.381mm) droop in the bar when measured over 4"/100mm in the five drilled holes. There is about 0.0005/ 0.01mm droop when the bar is mounted in the existing 5/8" hole. That hole appears reamed.
My other turret attachment's turret is bored 3/4" and I have a number of sleeves to accommodate the 1/2" and 5/8 " arbored tools I have. There is sufficient cast iron on PDW's turret to bore the holes out to 3/4" . How to bore the holes accurately is my next challenge. Any suggestions?
The tailstock turret has an advantage over the Hercus turret. Tools swing out of the way, they don't on the Hercus.
BT
* wobbles is an exaggeration. The movement is FA but at the end of a tool projecting 4 inches from the turret , it becomes a bit more than that.
Thank you Peter.The turret's arbor is a Jacobs Morse 2 to J6, a bit beefier than Chris's. The indexing mechanism isn't as beefy. It's simply a spring loaded detent pin with a tapered nose locating in a corresponding tapered seat. Corrosion and wear have taken their toll and the pin wobbles*. I made a replacement pin based on the dimensions of the original. The pin is a reasonable fit in the cast iron body but when located in the turret's indexing hole it needs to be pushed in hard to prevent turret movement. I measured the taper angle to be 9.5 degrees and made a series of tapered test cuts on some bar at and close to that angle to check the fit in the tapered hole. I'm thinking a longer nose on the pin might be an improvement.
I thought the turret's appearance would be improved with a bit of wire brushing and maybe a bit a wet and dry. Didn't do much to improve things so I took a light cut off. This is the hardest cast iron I have ever encountered with some areas harder than others.
Five of the the turret's tool mounting holes were bored slightly undersize, about 15.5mm. The remaining hole was exactly 5/8". Given the problems I have had with tailstock alignment I thought I would mount the turret in the headstock spindle and bore out the holes with a boring bar. At the lowest speed the finish was rough so I thought I'd have a go with the turret tailstock mounted. My plan was to use my imperial boring head until I discovered I'd swapped arbors on the thing and it was sporting a 30 taper. My Kaiser boring head came with a screw on 3M arbor but I didn't have a suitable draw bar for its installation in the Hercus so I went on to make two decisions that were my downfall.
I bored the holes with a 5/8 " slot drill only to find they were slightly undersize so I then used a 5/8" reduced shank drill bit mounted in a collet to open the holes up. May as well have been a licorice twist.
With a length of precision ground 4140 as a test bar, there is up to 15 thou (0.381mm) droop in the bar when measured over 4"/100mm in the five drilled holes. There is about 0.0005/ 0.01mm droop when the bar is mounted in the existing 5/8" hole. That hole appears reamed.My other turret attachment's turret is bored 3/4" and I have a number of sleeves to accommodate the 1/2" and 5/8 " arbored tools I have. There is sufficient cast iron on PDW's turret to bore the holes out to 3/4" . How to bore the holes accurately is my next challenge. Any suggestions?
The tailstock turret has an advantage over the Hercus turret. Tools swing out of the way, they don't on the Hercus.
BT
* wobbles is an exaggeration. The movement is FA but at the end of a tool projecting 4 inches from the turret , it becomes a bit more than that.
0 commentaires:
Enregistrer un commentaire