[OP]
Contributor
I like the idea of turning between centers and finishing the bottom first. That's the same ordering I use with the screw chuck of course. How do you get in to make the dovetail for the chuck with the tailstock in the way? I tried doing that and it seems impossible!
Contributor
John, I have a homemade scraper I use. It is profiled for the dovetail, and has two cutting edges - the front face, and the side dovetail. I remove a little material with the gouge first, and plunge carefully with the scraper - then move to the left to create the dovetail.
Keep in mind that your jaws are not thick, and the recess does not have to extend fully across the bottom. It just has to have enough room to insert your jaws at a particular diameter. You can remove the remaining waste later.
[OP]
Contributor
Ah. I've just been making them with a skew, sort of using it as a scraper to get into the corner. To do that, I pretty much need to be right where the tail stock is.
Member
Very carefully! Seriously, I use a dovetail scraper that I made. It was a HF scraper that I reground and cut the handle shorter. I have to have the tail-stock extended almost as far as it will go in order to insert the tool straight.Originally Posted by John Coloccia
I am toying with the idea of grinding a scraper so that the dovetail sticks out the side. It would have to be a negative rake scraper and sharpened from the top only to keep the shape consistent. I would probably want a long shaft to keep the handle clear of the turning platter, and I'm afraid the rotational forces would be hard to fight.
Retired - when every day is Saturday (unless it's Sunday).
Contributor
John, my "dovetail tool" is made from a power jointer blade - about 6" long, and 5/32" thick. I have several different profiles of scrapers that I use in a square metal tubing handle - see this thread.
Contributor
Thom, I haven't experienced any trouble with mine. And, I haven't found the rotational forces to be significant. I use 50mm jaws, and so I am cutting my recess at about 2" from center +/-, and only 1/8 - 3/16" deep. I relieve a little of the material with a bowl gouge - nothing more than a dip - then, with the tool rest very close to the work, I ease in the scraper. Mine is not negative rake, and has about 10-15* undercut on it. It isn't very wide, so it isn't creating a large recess.
[OP]
Contributor
Maybe I'll pick up a cheap scraper and use a grinder to grind the proper profile. Then I can just plunge straight and move left as you do, John. That seems a whole lot easier than what I'm doing even without the tail stock in the way. It's difficult to nail just the right angle freehand with the skew.
Contributor
John, it doesn't have to be a scraper - an old screwdriver will work, as well. I would probably prefer one with a "not round" shaft so it could rest flat on the tool rest and not roll. Or, regrind a spindle gouge you may not be using - about anything will work as you aren't using it much and it doesn't need sharpening often.
Member
I never liked the screw chuck. You have to drill a hole, mount the screw chuck in your main chuck, then turn, then take the screw chuck out, then mount the blank back in the chuck. If you have the proper sized forstner bit (within 1/8 inch of the size of your chuck jaws, which for me is 1 5/8 inches for my small chuck, and 2 5/8 inches for my large chuck) you simply drill a recess with the forstner bit in the top of the blank, and mount that way. You can use your tailstock to steady it if you want, but not really necessary unless you are doing bigger pieces. By the time you get to turning the recess or tenon for remounting, you can move the tailstock for easy tool access. Minimal pressure in the center of the bowl. I used to remove the chuck for remounting the blank, but have learned to feel when the blank is properly seated. If you are working with a big heavy blank, then it is easier to mount it like shown in the Jet video. I recently turned a 22 inch diameter Madrone bowl, and had to take the chuck off the lathe to mount that one. Not as strong as I used to be.
robo hippy
Member
Between centers, turn a recess for the chuck jaws, reverse, finish top, reverse again on the vacuum chuck to finish the bottom.
For between centers to begin, I guess a screw can be used in the chuck, but I just put one of those Oneway chuck spurs in to drive it against the tailstock. Some people just insert their morse taper spur drive, but not sure if that's good for the jaws or the taper if it gets spinning. There are other chuck spurs I see for sale, but I have not tried them. I usually do a number of pieces at a time for whatever stage of the process in order to save time in production. This gets around changing stuff on the lathe at every step for each piece. If you turn a lot of pieces, you're always thinking of how to be more efficient (that would be a good topic for another thread, huh). Reed's idea to drill a recess for the jaws during the first step between centers is a good one.
If you are limited in the thickness of the blank, then a glue block works great. Then a tenon can be used instead of a recess.
Member
I do platters in batches and work like this. I send the blanks trough the planer, thickness 22 mm. Got a jig on the bandsaw for cutting round blanks. After bandsawing I have got a centering mark on the up side of the blanks. On the pillar drill I have got a centering pin exactly under the center of the drill. I put the blank bottoms up on the centering pin, drill a 50 mm recess 3 mm deep, using a Forstner bit with the center ground away. Now the blank is ready for turning. I mount it on my chuck using the 50 mm jaws, now using a 12 mm sideground bowl gouge I can first turn the underside of the rim and then the inside of the platter without having to remount the blank. After turning I powersand what has been turned. Now what is left is the sanding of the foot and the recess. I do that by mounting the platter in homemade jaws for the chuck that fits the diameter of the platter. Using this methode I can turn and sand a 300mm(12 inch) platter in less than 10 minutes. The biggest batch I have done so far was 1000 300mm platters for one customer. Sorry for my English. Kurt Johansson
[OP]
Contributor
So you just make a recess. No dovetail?
Member
John
If starting with a dry planed board I double face tape to a face plate. With tailstock providing back up support I turn the bottom. Then remove the tailstock to create recess. Now flip into chuck to turn front side. Flip back on to vac chuck or jam chuck to fancy up the bottom if nessecary.
Good fabric double faced tape is good to hold many thing on the lathe. I use tape I buy at my local Ace Hardware.
Frank
'Sawdust is better than Prozac'
Member
Hello John
Just a recess and no tailstock. 12 inch platter -2000 rpm. Three drills with 2 inch homemade sanding pads, grits 120 and 150 open grit and one with 150 close grit attached to the sanding disks using hot melt glue.
Polishing using steel wool 000. Finish is an oil mix of BLO and Tung oil.
Kurt Johansson
Member
Hello John
Just a recess, no tailstock, 12 inch platter-2000rpm
Kurt Johansson
Posting Permissions
Reply With Quote