Glue Block Ratio

Re: Glue Block Ratio

John Lucas

>Your problem is not the size of the platter. It's either your parting technique or the wood you use as a glue block. I made 7 12" platters last year using 3" pine glue blocks. I would not suggest pine but this was a heavy solid type of pine.

I always reverse turn my platters so I glue the block on with CA glue. When I'm done with all but the foot I break the glue joint using a chisel. Then I reverse the piece and turn the foot.

When I do need to part off a platter I part it down to about an inch and use a saw with the lathe off to finish the cut.

Now to turn the bottom I use one of 3 ways. I have a large piece of wood mounted on a faceplate that I can turn a shallow recess to fit the outside of the platter. Then I use blue painters masking tape to hole it on the wood. Sometimes I use surgical tubing to hold it.

Another way is to use the large jaws designed for this purpose by the different chuck companies. The only problem with this is it requires a lathe with a larger swing than your platter diameter. My jaws expand out to about 17" so I can only do platters 15" or smaller.

The way I use most often now is a vacuum chuck. This holds the platter on the vacuum chuck. Because I make my own chucks they can be any size. It usually only takes a 6" chuck to do most platters up to 12".

Re: Glue Blocks

Mark Mandell - Gone Round In Jersey

>Tom,

Seems like it's a technique problem. In addition to John's good suggestions, if you reverse the platter and hold it on a jam chuck with your tailstock and a small cup center, you can cut off all of the block but a little 1/2" spud under the live center cup and turn the foot of your plate at the same time, then clean the rest by hand off the lathe. Simple jam chuck for this would be a piece of 2x8 fir mounted on a 3" faceplate, turned round with a slight dome and rounded-over edges, and faced off with some closed-cell foam like neopreen. Just take light cuts.

Good luck!

M

Re: Glue Block Ratio

Barry Irby

>John, the stuff I learn here is amazing. A couple of questions. You remove the glue blocks with a chisel? Do you just set the chisel on the glue line and tap it? Does the glue line break cleanly for you? Or do you split the glue block and then clean up the residue of wood and glue? Either way, do you pay attention to the grain of the wood, either the platter or the block?

I have Cole jaws for my chuck and they are smaller than the swing of the lathe, even fully extended so I made a set of hooks for them. Used inch wide flat steel strap and bent a hook on the end of each of eight. Set them in a jig on the drill press and put a hole in each. Dipped the hooked end in rubber for coating tool handles. Now they expand the jaws to match the swing of the lathe. (less clearance) They work much better than the rubber bumpers that came with the jaws.

I would have never thought to try blue tape to hold a platter in a jamb chuck. Do you also press it in with the tail stock? Seems it would work for sanding but the first cut would rip it right out.

And back to the original question, get smaller face plates, I have a Nova DVR and use 3" and 4" face plates for nearly everything.

Re: Glue Blocks

TomW in SouthJersey

>Thanks to both of you. I'll try all the techniques you suggested. I'm sure I find one that fits different situations best.

Part of my problem was I had some pine blocks give out on me so I've been using hard maple which is hard to part off.

I'm considering making a vacuum chuck. I haven't used one but it seems very convenient for this type of application. I also don't have a good quality chuck yet. I currently using an old Grizzly 3 jaw chuck. I'm planning on getting a Oneway Talon soon.

Let's see. Add on the Wolverine or Sorby grinding jig to that I'm looking at. I better sell some bottlestoppers or something.

Thanks again for the advice. I use everything I learn here.

Re: Vacuum

Mark Mandell - Gone Round In Jersey

>Tom,

When (if) you go the vacuum route, DO NOT fail to keep your tailstock engaged for all but the last bit of the operation where it will be in the way. In fact, I often use my vacuum chucks as jam chucks and only turn on the pump when I'm ready to disengage the tailstock.

M

Re: Vacuum

TomW in SouthJersey

>Mark - Does that offer for some walnut or cherry still hold? It was the sympathy offer you made after I posted that I spent $238 for one chunk of maple.

Tom

Re: Just Say

Mark Mandell - Gone Round In Jersey

>When you're coming up [weekends only, please]

M

Re: Tape

Mark Mandell - Gone Round In Jersey

>Barry,

Seem to remember someone using shrink/stretch wrap like is used on pallets and for binding boxes together. They said it holds like a bear, but is easy to get off and no icky stuff on the bowl.

M

Yup, that was me

Mike Schwing from Md.

>My first "paid" tip to the AAW magazine. Put the work in the jaws, tighten as normal and then use the packing/stretch wrap all around it, covering the glue block if necessary. When its good and tight, you can use an x-acto knife to cut the plastic wrap from around the area you need to work. Works like a dream!

Also - I do almost the exact things that John does for his, but I don't use CA because I've had it fail. Probably is my technique. I use 5 minute epoxy instead, never had one let go. I also use a think kerf saw to part off the glue block while on the vac chuck, if it is big enough to reuse. If not I simply turn it away.

Re: Glue Block Ratio

John Lucas

>Barry

I use a bunch of different methods for glue blocks depending on the what I need. Most often I use CA glue. If you use accelorator it makes a joint that is fragile to impact. I put the tip of the chisel on the joint and hit is sharply. I'm not trying to pry the joint apart just cause enough impact to break the joint. Most of the time it will break at the glue line. If you don't use accelorator it will usually break the wood.

I use a paper joint on occasions where I can't take any chance of tearing the wood.

I use yellow glue if I have plenty of time and intend to turn the glue block away. Yellow glue is a lot cheaper than CA.

To glue blocks on wet wood I use Gorilla glue.

Sometimes I use 5 minute epoxy but it's kind of expensive also so unless I need to turn something right then I use one of the other methods.

Re: Vacuum

John Lucas

>Ditto on the tailstock. I always use a tailstock until I have to move it to make the final cuts. I hate losing pieces that fly off the lathe when having the tailstock there would have prevented it.

Re: Vacuum and tail stock?

Ron in Drums PA

>Does it happen often that the piece flys off when using a vacuum?

I'm in the middle of building a vacuum setup, and I thought it was going to be a cure all.

Maybe There's a Better Way...

Wally Dickerman

>Yes, you do need a smaller faceplate. The 3 inch size is the one you'll most of the time.

I use glue blocks for most of my bowl and vessel turning. However, I think there's a better way for platters. I've made lots of platters, and I've tried various methods of fastening the blank to the lathe. 4-jaw chuck, glue block, jam-fit chuck, hot-melt glue, but the best in my opinion is double faced tape. (I did a demo on just that at our club last Saturday)

There are several things that you must do to successfully use tape. You must use the correct tape. Carpet tape is unreliable, and so is any kind of paper tape. The best I've found is Permacel, a cloth tape, as sold by Craft Supplies, Packard and others.

My method is to first mount the blank, using a screw chuck. A faceplate, or the screw center that comes with most 4-jaw chucks will work. I turn the base to prepare it for the tape. In fact, I turn the whole underside of the platter at this time. The area for the tape must be true and flat, just as if you were making a glue joint. I sand that area down to 600 and turn a small design on it. The faceplate I'd use for a 12 inch platter would be a 3 inch one. (The size formula that I use for the foot of a platter is 2/5th to 1/2 the diameter of the platter). I got that from Ray Key, who has made and sold many hundreds of platters. The tape is applied to the faceplate, which is then centered and mounted on the blank. You must clamp it securely for a minute or two. I use a large wooden parallel clamp. After reversing the piece and completing the turning, I remove the piece by inserting a 1/2-inch thick turned plug into the opening on the faceplate, remounting the piece, As you slowly thread the faceplate on the spindle the plug easily pushes the finished platter off the faceplate. (I got $75 from Wood Magazine for that tip) It was later published in the American Woodturner. If you've done this properly, you can trust the tape to hold. In fact, you can't pull it off if you try.

I've turned platters up to 22 inches using a 6 inch faceplate and tape.

Double faced tape won't work with wet wood.

Wally

Re: Vacuum and tail stock?

Mark Mandell - Gone Round In Jersey

>Ron,

With a vacuum set-up, you're always depending upon a thin line of contact between the bowl and the chuck to maintain the seal and hold the piece. Since you know that the wood flexes during a cut (especially when you're turning that nice light piece with the uniformly thin bottom), your piece can easily deform just enough to break the seal and lose all your vacuum. Then you get to play follow-the-bouncing-bowl. Where the vacuum really shines is finishing that last little bit in the center and then sanding and finishing the foot evenly. With a good strong vacuum you can do a lot of cutting, but with the tailstock engaged you can focus all of your attention to that cut instead of having one corner of your mind wondering "if the thing's gonna let go on me and what do I do if it does?"

I like surprises . . . except when I'm poking a piece of wickedly sharp steel into a piece of spinning wood. I also really hate blowing up a piece when I put all that time into it and I'm at the point of being able to say "See, Mom? I made this Big Thing!"

|;-}}

M

Re: Vacuum and tail stock?

Stuart Johnson

>Just remember to turn off the lathe and then the vacuum. I was finished up a piece yesterday and reached up and switched off the pump first. It banged all over the place before I got the lathe shut off but for some unknown reason there wasn't a mark on the bowl.

Well if you put it that way

Ron in Drums PA

>it make allot of sense, Thanks!

Sometimes you gets lucky

Ron in Drums PA

>

Re: Well if you put it that way

Mike Schwing from Md.

>Just like Mark and John, I keep the stock in place as long as possible, too. I have "levered" a piece or two off due to forgetting that light cuts were needed, and the tailstock would have prevented it. I now use it exactly as Mark does, with one exception.

I leave the vacuum on the whole time for 2 reasons. I don't apply any pressure with the tailstock, just use it to keep the thing in place in case of a catch or a heavy mistaken cut that might lift it off otherwise.

1. so it doesn't slip off center even a scooch

2. because if I suddenly turn on the vac when I'm all but done the center nub, if the bottom is a thin one, you can watch the bottom of the bowl you just finished being sucked in due to it being thin. It won't necessarily break, but if the vac is on the whole time I can watch the progress and I get a good idea of how thin the bottom is getting by the deflection due to vacuum. I don't like to adjust the vac once the workpiece is seated, but that could be done as an alternative.

I'm no pro, this is just what I do.

Re: Well if you put it that way

Ron in Drums PA

>Mike Wrote:

if the bottom is a thin one, you can watch the bottom of the bowl you just finished being sucked in due to it being thin. It won't necessarily break,

Ron's Question

With a run of the mill gast vacuum pump, can you crank up to much vacuum to crack a bowl?

Re: Well if you put it that way

Mike Schwing from Md.

>I'm not sure what a "run of the mill gast pump is" but I suspect that is exactly what I have. The answer is "you bet!". I can consistenly pull 25" of Hg with mine, and you can definitely implode a bowl or hollow form with 3/16" walls. Surely not every time, but it can happen. When I start to approach that dimension, I almost always can see a deflection from the vac.

You can also notice that a bowl that has been sanded creates a better vac than one that has not, the finer grit you go, the better the vac, too. That is a fact worth remembering, because if you finish off the bottom using your vac and then you start to sand the exterior of your bowl, the vacuum will get stronger and stronger as you go. If you put a sealer on - even more so. I don't normally apply a finish with the vac on because it pulls it through the surface, and can pull bubbles into one if you finish the interior first and then put it on the vac.

Thanks Mike

Ron in Drums PA

>

6" vac chuck?

Doug

>Not sure I understand your statement. Do you need a 6" dia vac chuck to hold a 12" platter?

Re: Vacuum and tail stock?

Barry Irby

>The only reason you didn't see the marks on the bowl is because it hit you in the head first and you have joined the Stevie Wonder wood turning club. Just be glad you didn't join the Ray Charles Chapter.

Re: Maybe There's a Better Way...

TomW in SouthJersey

>Wally

I tried some double faced tape on a couple small items without any success. I saw it used at a woodworker show last fall (I don't remember whether it was at the Edison, NJ or Fort Washington, Pa. show).

I must be using the wrong tape. I'll try some of the tape you mentioned. It seems tape would also come in handy for turning collars for hollow forms.

I also intend to try the set up Bill Grumbine shows in his DVD for cleaning up the bottom of bowls.

I'd have much more time to learn this stuff if work didn't get in the way.

Thanks to everyone for all the advice.

Tom