Ambrosia Maple Hardness Que.

[Stan Smith]

I'm turning a large (approx. 11" x 4") goblet using ambrosia maple. I turned it into round and mounted it my vicmarc chuck. I wanted to turn some pens for Christmas so I removed the chuck with the stock still in it. I thought it was pretty well dried out. It was waxed when I bought it and I let it set in a cabinet until the moisture content was down to 12%. I think that it's dried out even more and now the wood is really hard and tough even with sharp tools. I used some ambrosia maple for some bird house Christmas ornaments and it was not difficult to work with at all. I've also had problems keeping it in round. I've been using a Harrison round carbide tool for hollowing. I really have to be careful and take very light cuts or I'll get a catch. I stopped using my gouges because of catches. I think the catches are caused in part with me dealing with a very slight wobble. I sort of feel like I've painted myself into a corner by starting and stopping over too long a period of time.

I have drilled a 1/2" hole in the inside for the depth. I've been using my Berger tool some in the hole, but I have to take it easy there, too. I guess my question is about working with real hard woods. If I continue, at my current pace, it will take a long time to get the inside hollowed out using my current method. I should also mention that I'm also using the PSI steady rest. I did bring up the tail stock when mounting the steady rest. I guess I could just admit defeat and move on to something else. Sometimes that's the most practical solution, but I would like to hear what others think since I have very little experience turning hard, fry, wood. Thanks for any comments.

stan

[Roger Chandler]

Stan, the wobble you are experiencing is likely due to the fact the wood moved as it dried, making the ability to put it back on the lathe and run true very slim. If you have enough material to true up the hold [tenon or recess] and re-chuck the piece, then you will be able to complete in a better fashion.

Hard, dry woods do present their own set of issues, but can be overcome by light cuts and persistence. When hollowing, make sure your cut is just a smidgen above center line.......in my experience some woods require you to finness the cut and find the sweet spot with the rpm of the lathe and the position of the cutter you are using. You will likely need to use a steady rest of some description to help avoid the wobble, as the longer the piece the more stability issue you will encounter with the side pressure put on the piece by the cut..........steady rests are important for helping a hollow form to run true.

if you cannot get a true hold on the chuck, then I would try to face the thing off and use a faceplate, then re-true the form completely, provided you have enough wood left to do that.

[Stan Smith]

Thanks for your reply, Roger. You've given me some hope, at least with "..light cuts and persistence." I think that I've done too much shaping, inside and out, to go the faceplate route now. As I said, I am using a steady rest. I was struggling somewhat to get it adjusted right until I used the tailstock with a live center. That works well for the outside, but the inside is very touchy. I've already put it back between centers for truing a couple of times. I guess he wood "moved" more than I thought.

I have tried to get the tenon for the chuck right a few times. I always reseat the stock before I turn the lathe on. I have a Jet midi so I have to take the tailstock off to access the inside. Another problem is positioning the steady rest because of the stays on the bottom side of the lathe bed. This project is more involved than I thought it would be. I'm planning to give this goblet to our church, but it will be the last big one that I do. Again, Thanks.

[Pat Scott]

Stan sometimes no matter how dry the wood is, it's still going to move and warp because you're relieving internal stress. All you can do is get through it as best as possible. Trust me when I say the more you mess with it, the worse it gets!

If you have enough mass left, you can true the outside one more time. Then sand the outside and don't touch it again. Now hollow the inside by truing up the rim and setting your wall thickness. The thinner you go the more movement you can get, so it may be that what you have now is the final thickness. Accept that this piece might not be the best you've ever done - but also you are your worst critic and others won't see imperfections like you do.

[Stan Smith]

Thanks, Pat. Those are helpful comments.

Are you saying to turn the stem to the final dimensions before hollowing out the inside? I think that I'm confused because I thought I was supposed to do the hollowing first. The inside depth is 3.5" and I've already done 1.5".

[Pat Scott]

Sorry for the confusion, I was talking about finishing the cup to final dimensions and shape. Always do the cup completely (including sanding) before ever starting on the stem. If you've gone 1.5" deep, before you go any deeper make sure the outside of the cup is shaped the way you want. If it is, then hollow the rest of the way and get done with it. Sand the inside and outside of the cup and don't touch it again except to put finish on it. At this point you should have a rough cylinder with a finished cup on the end. Now you can start reducing the cylinder to make the stem. If the stem is long, you may have to do a bit at a time instead of trying to do the whole stem all at once. If the cup starts whipping around too much while you're working on the stem, you can wad up a kleenex or bit of paper towel and put it inside the cup, then gently bring up the tailstock.

[Stan Smith]

Thanks for the clarification, Pat. I'm going to try and do a little more rounding with the tailstock in place. I also plan on using it to finish the outside, after the inside, with the tailstock in place using a rubber chucky. It's a plastic/vinyl that goes over a live center. I just use the tailstock whenever I can rather than risk a "problem." Thanks again for your detailed advice.

[Stan Smith]

I'm making progress. Every time I get even a small catch, I stop the lathe, slightly loosen the chuck jaws,bring up the tail stock and tighten it, and then re-tighten the chuck jaws and remove the tailstock. Also have to adjust the steady rest wheels sometimes. Sometimes I turn from the middle out and sometimes from the outside in. This seems weird to me since I think it would be one way or the other?

I'm thinking that whey I get down to an inch, I'll use my Berger tool to complete the inside.

[Stan Smith]

I'm making progress. Every time I get even a small catch, I stop the lathe, slightly loosen the chuck jaws,bring up the tail stock and tighten it, and then re-tighten the chuck jaws and remove the tailstock. Also have to adjust the steady rest wheels sometimes. Sometimes I turn from the middle out and sometimes from the outside in. This seems weird to me since I think it would be one way or the other?

I'm thinking that whey I get down to an inch, I'll use my Berger tool to complete the inside.

Even though I'm trying to be careful and concentrate, I'm getting small catches. I finally concluded that the PSI steady rest is just not designed right for my project. I've seen some youtubes with turners using steady rests bigger and with thicker metal than my steady rest. If I get even a slight catch the arms on my steady rest are moved up or down and no longer make contact with the wood. I guess you get what you pay for although I think the psi rest would be okay for smaller spindle projects. I know that I could make my own, but I've ordered a bigger steady rest made from welded metal stock. I literally spent more time trying to get my psi rest set right than I did turning. I plan on using the new rest (demo'd by Carl Jacobson) for other projects. Now it's just wait and see. I'll post again after I have a chance to try it.