bergerud
05-01-2011, 10:05 AM
I have spent hundreds of dollars and hundreds of hours trying to “solve” my Carvewright chuck problems. From buying Sears QCs on ebay, to cannibalizing old routers and die grinders for chucks, and now buying ER collect chuck extensions. (These are used in the milling industry to extend chucks down into the work.) The ER collet chucks are an order of magnitude (in some cases two orders!) more accurate than the chucks we are used to. They are small, light, and versatile. Consider some pros and cons of this collet system for the Carvewright compared to the available 1/2 inch chuck systems.
Pros:
Smaller run out for smoother carves, less cutting torque, and longer bit life.
Less rotational inertia for easier cut motor and flex shaft spin up.
Less mass for less wear on the y and z drives.
Versatility in holding any size bit, carbide or otherwise without annoying single size adapters.
Freedom to experiment with inexpensive bits from the huge selection of carbide bits on the market.
Cons:
At this point, you have to convert it yourself and this requires a lathe and some skill. (A third party machined spindle may become available.)
Changing bits is more awkward requiring two wrenches.
Consistent bit depth in multi-bit projects requires collars or a plug.
There is a risk of voiding warranty on machines under warranty.
You will not buy a CT or CT bits and support LHR. (seriously)
YOU NEED A LATHE
I had originally hoped that I could come up with a way in incorporate the ER spindle system to the Carvewright without any, or at least minimal lathe work. I have to admit defeat. The unavailability of metric bearings to match the Carvewright truck with the available shank sizes, and the more important fact that, the available metric shank chucks from China can have unacceptable run outs. These chucks are fine, but both bearing journals must be turned to guarantee the chuck comes out straight. The process of adapting the ER spindle system that I am about to describe is not for everyone. If you are not so mechanically inclined, you should probably go with the Carve Tight spindle from LHR. If, on the other hand, you are mechanically gifted, have access to a lathe, and you cannot be stopped from trying the ER spindle on your Carvewright, consider the following procedure.
BUY AN ER COLLET CHUCK
Buy an ER11 collet chuck extension with a shank diameter of 16mm or 5/8”. (You will also have to by at least one 1/4 inch collet.) Ideally, the over all length should be 3 inches. (If it is longer, it will have to cut off later in the process.) The threaded draw bolt threads must be M8 or 5/16. These collet chucks range in price from $12 to $150. The cheaper you go, the more you may have to compensate for run out. On the other hand, there is no point in buying an expensive one since the final accuracy will be determined by how you turn it, not on its initial run out.
TURNING PROCEDURE
Place a 3 inch long piece of 5/16” bolt shank (higher the grade the better) tightly in your lathe chuck and have at least 1 inch protruding. Carefully turn down the protruding 1 inch to a ¼” diameter machine finish. This gives you a “perfect” stub with virtually no run out to attach your collet chuck to. (The required accuracy of this turn job is beyond most 3 jaw chucks, the stub is essential to minimize run out.)
Tightly thread a short bolt into the draw bolt hole. The bolt should have a smooth face on the head as it will be center drilled. Attach the collet chuck with a ¼” collet to the stub and tighten. (Gently wiggle the shank around as you tighten to make the collet center in the taper.) Spin the lathe slowly or by hand and note the run out of the shank. If you bought a cheap collet chuck, the shank end could have a significant wobble. (I suggest you measure it with a dial indicator and mark the high point. Reattach the collet chuck to the stub, rotating the collet 180, to make sure the run out is not due to the collet. If it is, you need a better collet.)
Very carefully center drill the bolt head on the end of the shank. I suggest you use a miniature center drill so that the center drill does not tend walk on the bolt head. You do not want to alter the wobble. Detach and reattach to check your center hole. If the center hole wobbles (or the dial indicator does not agree with the initial wobble measurement), put in another bolt and try again. Once you are happy with the center hole, you can, with the collet chuck between the stub and a lathe center, turn the shank to the profile of the carvewright spindle. (You will, of course, like carbide lathe tools, these shanks are hardened.) Either copy your old Carvewright spindle or see the attached diagram for the dimensions. The bottom bearing boss should give a tight (interference like) fit requiring a press (vise!) to slide the bearing on. The top bearing should be only a snug fit so that a few pounds force slides it on. (Otherwise installation of the spindle in the truck will require a press.) Unless you are a machinist, I suggest you turn the bosses close with the lathe tool and then fine tune with a small file and emery cloth. After the shank is cut off (if it needs to be) and the center is backed away, the file and emery can be used as you test the fit of the bearings.
THE SQUARE FLEX SHAFT HOLE
The hollow shank now has to have the last 1/2 inch of the center hole plugged. There are a few choices here depending on the chuck you bought.
If you bought a 3 inch long chuck with threads in the end, simply find a bolt with ½” of threads which has a shank the same diameter as the outside of the threads. (not a bolt with a thin shank) Using red Loctite, thread it in and gently tighten. Cut it off flush, file smooth.
If you bought a long shank chuck with back up screw threads all along the inside bore, the same procedure as above will work after you cut it off.
If you bought a long shank, cheap chuck with only draw bolt threads in the end, there will be no threads inside after you cut it off. To make matters worse, the bore hole is probably not even centered. Tapping threads is tough since the shank is hardened. (You only need a few or shallow threads and you can make it work like above with red Loctite.) Another method I tried was to press in a small ½ long plug into the bore and braze the end. Push the plug in an extra 1/16” and fill the hollow with brass. Not pretty but you bought the cheap one!
Put the collet chuck back on the stub and carefully (or use a center rest) drill a 5/32” or #21 hole through the ½” long plug bolt. (accuracy here is not so critical) The lathe work is now done. The square hole for the flex shaft can be hand filed with a small 1/8” square file in about an hour. Use a fine permanent marker to draw a reference square around the hole. File in the corners mostly and keep the original drill marks inside on the flats as a reference until the end. It is useful to make a file handle with a ¼” shaft so that the collet can be used as a guide near the end of the filing. Test with a flex shaft end as you get near.
SPINDLE INSTALLATION
To install the new spindle, first press the large bottom bearing onto the spindle. This can be done, for example, with a vise and a deep socket (Maybe a washer between the inner bearing race and the socket, and a piece of hardwood to protect the collet nut from the vise.) Now, with the top tolerance ring and wave washer in place press the small top bearing into the top of the truck. Take care to push it in square. Put a wood 2x6 in the Carvewright under the truck and clamp the machine down on it. Raise the truck up, insert the lower tolerance ring and then insert the spindle from below. You should be able to align the top of the shaft into the top bearing before you push in the bottom bearing. Put another ½” or thicker small block of wood under the spindle. Now push the truck to the bottom until the spindle hits the block. By pressing straight down from above on the truck, you should be able to finish pushing in the bottom bearing. The top bearing may have lifted up. Use the old bearing on top and a piece of wood to gently push the bearing back down. Put on the snap ring and the flex shaft receptacle and you are done. Make sure, however, that the snap ring is in the slot all around. You may have to gently push it down. (use the old bearing again).
NOTES:
1. Do not buy metric collets. You really want imperial sizes to snugly fit your bits. They will be more accurate and easier to use. They will cost more. ($60 for a {1/32,1/16,3/32,1/8,3/16,7/32,1/4} set or 8.50 each. See Shars.com)
2. Stay away from the ER11M with the mini nuts. These nuts are for close quarter milling where the chuck goes down into the carving. We do not do that and there is no reason to deal with finicky fine threads, and small nuts. Ok for bigger ERs but too small for ER11. They do look nice!
3. I recommend spending $50 on the collet chuck See www.shars.com or www.maritool.com (http://www.maritool.com/) . It will be easier than a $15 one from China. The extra problems of off centered bore holes or no threads inside, etc. are not worth the savings.
4. As a first test of the new chuck, do a few short “break in” carvings. The new bearings will get very hot if you bought standard bearings (6002DU and 6000DU) from the friction of the seals. Better if you order 6002V and 6000V as these bearings have no contact seals for high rpm and spin very freely. (The original bottom bearing on my B machine was 6002V.)
5. If one likes multi-bit projects, one needs consistent bit length when changing bits. You would think one could buy extra collets and “glue” them onto the bits with blue Loctite. (Loctite works well to glue carbide to adapters) This will work but you would also need extra nuts as well. The collets do not come out of the nuts when the bit is in the collet. (In fact, the nut is attached and pulls the collet out of the taper when unscrewed.) It looks like its back to small collars on the bits. One could also plug the collet chuck but then long bits are a problem. Not a strong point for the system.
6. One could also use an ER16 collet chuck. These hold bits up to 3/8”. The jump in size, however, of the collets and nuts seems disproportionate. Especially since we do not need to use 3/8” bits; 1/4” inch bits can accomplish any task we want. The ER20 holds up to 1/2 inch bits but do not even think about it. (back to flywheels!) The ER16M with the mini nut might be worth a try for those who like to experiment.
7. If you do make, or have made an ER spindle for your machine instead of buying a Carve Tight and bits from LHR, promise to use the money you save to buy software from LHR. (We do want to keep the lights on at LHR. I want a model D!).
Pros:
Smaller run out for smoother carves, less cutting torque, and longer bit life.
Less rotational inertia for easier cut motor and flex shaft spin up.
Less mass for less wear on the y and z drives.
Versatility in holding any size bit, carbide or otherwise without annoying single size adapters.
Freedom to experiment with inexpensive bits from the huge selection of carbide bits on the market.
Cons:
At this point, you have to convert it yourself and this requires a lathe and some skill. (A third party machined spindle may become available.)
Changing bits is more awkward requiring two wrenches.
Consistent bit depth in multi-bit projects requires collars or a plug.
There is a risk of voiding warranty on machines under warranty.
You will not buy a CT or CT bits and support LHR. (seriously)
YOU NEED A LATHE
I had originally hoped that I could come up with a way in incorporate the ER spindle system to the Carvewright without any, or at least minimal lathe work. I have to admit defeat. The unavailability of metric bearings to match the Carvewright truck with the available shank sizes, and the more important fact that, the available metric shank chucks from China can have unacceptable run outs. These chucks are fine, but both bearing journals must be turned to guarantee the chuck comes out straight. The process of adapting the ER spindle system that I am about to describe is not for everyone. If you are not so mechanically inclined, you should probably go with the Carve Tight spindle from LHR. If, on the other hand, you are mechanically gifted, have access to a lathe, and you cannot be stopped from trying the ER spindle on your Carvewright, consider the following procedure.
BUY AN ER COLLET CHUCK
Buy an ER11 collet chuck extension with a shank diameter of 16mm or 5/8”. (You will also have to by at least one 1/4 inch collet.) Ideally, the over all length should be 3 inches. (If it is longer, it will have to cut off later in the process.) The threaded draw bolt threads must be M8 or 5/16. These collet chucks range in price from $12 to $150. The cheaper you go, the more you may have to compensate for run out. On the other hand, there is no point in buying an expensive one since the final accuracy will be determined by how you turn it, not on its initial run out.
TURNING PROCEDURE
Place a 3 inch long piece of 5/16” bolt shank (higher the grade the better) tightly in your lathe chuck and have at least 1 inch protruding. Carefully turn down the protruding 1 inch to a ¼” diameter machine finish. This gives you a “perfect” stub with virtually no run out to attach your collet chuck to. (The required accuracy of this turn job is beyond most 3 jaw chucks, the stub is essential to minimize run out.)
Tightly thread a short bolt into the draw bolt hole. The bolt should have a smooth face on the head as it will be center drilled. Attach the collet chuck with a ¼” collet to the stub and tighten. (Gently wiggle the shank around as you tighten to make the collet center in the taper.) Spin the lathe slowly or by hand and note the run out of the shank. If you bought a cheap collet chuck, the shank end could have a significant wobble. (I suggest you measure it with a dial indicator and mark the high point. Reattach the collet chuck to the stub, rotating the collet 180, to make sure the run out is not due to the collet. If it is, you need a better collet.)
Very carefully center drill the bolt head on the end of the shank. I suggest you use a miniature center drill so that the center drill does not tend walk on the bolt head. You do not want to alter the wobble. Detach and reattach to check your center hole. If the center hole wobbles (or the dial indicator does not agree with the initial wobble measurement), put in another bolt and try again. Once you are happy with the center hole, you can, with the collet chuck between the stub and a lathe center, turn the shank to the profile of the carvewright spindle. (You will, of course, like carbide lathe tools, these shanks are hardened.) Either copy your old Carvewright spindle or see the attached diagram for the dimensions. The bottom bearing boss should give a tight (interference like) fit requiring a press (vise!) to slide the bearing on. The top bearing should be only a snug fit so that a few pounds force slides it on. (Otherwise installation of the spindle in the truck will require a press.) Unless you are a machinist, I suggest you turn the bosses close with the lathe tool and then fine tune with a small file and emery cloth. After the shank is cut off (if it needs to be) and the center is backed away, the file and emery can be used as you test the fit of the bearings.
THE SQUARE FLEX SHAFT HOLE
The hollow shank now has to have the last 1/2 inch of the center hole plugged. There are a few choices here depending on the chuck you bought.
If you bought a 3 inch long chuck with threads in the end, simply find a bolt with ½” of threads which has a shank the same diameter as the outside of the threads. (not a bolt with a thin shank) Using red Loctite, thread it in and gently tighten. Cut it off flush, file smooth.
If you bought a long shank chuck with back up screw threads all along the inside bore, the same procedure as above will work after you cut it off.
If you bought a long shank, cheap chuck with only draw bolt threads in the end, there will be no threads inside after you cut it off. To make matters worse, the bore hole is probably not even centered. Tapping threads is tough since the shank is hardened. (You only need a few or shallow threads and you can make it work like above with red Loctite.) Another method I tried was to press in a small ½ long plug into the bore and braze the end. Push the plug in an extra 1/16” and fill the hollow with brass. Not pretty but you bought the cheap one!
Put the collet chuck back on the stub and carefully (or use a center rest) drill a 5/32” or #21 hole through the ½” long plug bolt. (accuracy here is not so critical) The lathe work is now done. The square hole for the flex shaft can be hand filed with a small 1/8” square file in about an hour. Use a fine permanent marker to draw a reference square around the hole. File in the corners mostly and keep the original drill marks inside on the flats as a reference until the end. It is useful to make a file handle with a ¼” shaft so that the collet can be used as a guide near the end of the filing. Test with a flex shaft end as you get near.
SPINDLE INSTALLATION
To install the new spindle, first press the large bottom bearing onto the spindle. This can be done, for example, with a vise and a deep socket (Maybe a washer between the inner bearing race and the socket, and a piece of hardwood to protect the collet nut from the vise.) Now, with the top tolerance ring and wave washer in place press the small top bearing into the top of the truck. Take care to push it in square. Put a wood 2x6 in the Carvewright under the truck and clamp the machine down on it. Raise the truck up, insert the lower tolerance ring and then insert the spindle from below. You should be able to align the top of the shaft into the top bearing before you push in the bottom bearing. Put another ½” or thicker small block of wood under the spindle. Now push the truck to the bottom until the spindle hits the block. By pressing straight down from above on the truck, you should be able to finish pushing in the bottom bearing. The top bearing may have lifted up. Use the old bearing on top and a piece of wood to gently push the bearing back down. Put on the snap ring and the flex shaft receptacle and you are done. Make sure, however, that the snap ring is in the slot all around. You may have to gently push it down. (use the old bearing again).
NOTES:
1. Do not buy metric collets. You really want imperial sizes to snugly fit your bits. They will be more accurate and easier to use. They will cost more. ($60 for a {1/32,1/16,3/32,1/8,3/16,7/32,1/4} set or 8.50 each. See Shars.com)
2. Stay away from the ER11M with the mini nuts. These nuts are for close quarter milling where the chuck goes down into the carving. We do not do that and there is no reason to deal with finicky fine threads, and small nuts. Ok for bigger ERs but too small for ER11. They do look nice!
3. I recommend spending $50 on the collet chuck See www.shars.com or www.maritool.com (http://www.maritool.com/) . It will be easier than a $15 one from China. The extra problems of off centered bore holes or no threads inside, etc. are not worth the savings.
4. As a first test of the new chuck, do a few short “break in” carvings. The new bearings will get very hot if you bought standard bearings (6002DU and 6000DU) from the friction of the seals. Better if you order 6002V and 6000V as these bearings have no contact seals for high rpm and spin very freely. (The original bottom bearing on my B machine was 6002V.)
5. If one likes multi-bit projects, one needs consistent bit length when changing bits. You would think one could buy extra collets and “glue” them onto the bits with blue Loctite. (Loctite works well to glue carbide to adapters) This will work but you would also need extra nuts as well. The collets do not come out of the nuts when the bit is in the collet. (In fact, the nut is attached and pulls the collet out of the taper when unscrewed.) It looks like its back to small collars on the bits. One could also plug the collet chuck but then long bits are a problem. Not a strong point for the system.
6. One could also use an ER16 collet chuck. These hold bits up to 3/8”. The jump in size, however, of the collets and nuts seems disproportionate. Especially since we do not need to use 3/8” bits; 1/4” inch bits can accomplish any task we want. The ER20 holds up to 1/2 inch bits but do not even think about it. (back to flywheels!) The ER16M with the mini nut might be worth a try for those who like to experiment.
7. If you do make, or have made an ER spindle for your machine instead of buying a Carve Tight and bits from LHR, promise to use the money you save to buy software from LHR. (We do want to keep the lights on at LHR. I want a model D!).