chainsaw on the lathe

[turnerted]

G'day
I have a rosewood blank 370mm diam.x 100mm thick which I want to cut in two to make two platter blanks .
The way I have done this before is to mount the blank on the lathe and make a series of cuts around it with the chainsaw , locking the lathe for each cut with the index pin but I have found that no matter how carefull I am ,the cuts are never square and I end up loosing at least two times the thickness of the chainsaw .
I am tempted to try cutting with the lathe running slowly in reverse and the chainsaw resting on the toolrest . I am sure this would be a more accurate way of cutting . Has anyone tried this ? or will something disasterous happen . I would put a piece of ply across the ways to protect them if the saw goes through quicker than expected and release the tails stock just before the cut goes through .
What do you reckon ? or are there other suggestions on ways to tackle this . The only other suggestion I have heard of was a giant parting tool made from a file and a long handle .
Ted

[cornucopia]

flippin eck :o the chainsaw method sounds very dangerous and old file's can snap very easily.

at 370 mm you can use a standard parting tool so far and then you could use the sorby slicer or just simply hand saw the rest.

[Calm]

I would suggest using the parting tool for as deep as you are game then use a handsaw to finish. The parting tool should give you a very good guide as to where to cut. Or then take it off and fiinh the cut with the chainsaw.

Not sure i woud use the chainsaw with the lathe running:no::no::no::doh::doh::o:o

Cheers

[Skew ChiDAMN!!]

I think I'd look at making a tilting jig for your chainsaw, basically just a hinge system to attach it to your lathe. It should be more accurate than freehanding.

I certainly won't recommend using one with the lathe running... (I don't think I'd ever try it, but then again when I was younger I didn't think I'd be stupid enough to do half of what what I do now. :rolleyes:)

[weisyboy]

just cut streight thrrew in oen pass mutch more accurate than lotsa little passes.:2tsup:.

or make a mini alaskan mill.

[joe greiner]

Definitely do NOT do this with the lathe in reverse. The cutting force could unscrew whatever is holding it to the headstock spindle. BTW, how is the blank attached in the first place?

The only way I could entertain this notion would be with a tilting contraption, like Skew says, but attached on the other side of the bed, so that the chainsaw cut opposes the normal lathe rotation. A Japanese pull saw might also work, but for anything above the workpiece, the kerf will tend to pinch the blade or bar as the workpiece "bends." The pull saw below the workpiece, from the normal turner's position might work better, because the kerf there gets wider as the workpiece bends; also makes a smaller kerf and less waste. I haven't tried it myself, but I think Japanese turners do something like it. A hacksaw blade, with the teeth properly oriented, could also be used in pulling mode below the workpiece to alleviate buckling.

All things considered, it might be better to have the blank precisely cut by bandsaw mill, and use the fresh-cut faces for mounting the two new blanks - probably more yield this way.

Cheers,
Joe

[Paul39]

Running at your slowest speed, I would cut 25 to 50 mm deep with a parting tool, then finish with a very sharp, stiff hand saw in the groove, stopping just before the two parts become unstable if between centers.

Not good to have two pieces of timber come flying at you with a saw between.

Stop the lathe and finish by sawing through by hand, on or off the lathe.

The groove will keep the saw blade more or less straight, the thinner blade will save wood.

[Ed Reiss]

Use a bandsaw to resaw the blank in two.

Using the lathe/chainsaw combo that way could lead to unwanted :o:C results.

[ElizaLeahy]

:oo:

I read this before I had my morning coffee and BOY did it wake me up!

Don't need coffee. Having nightmares and I'm pretty sure I'm awake now!

[weisyboy]

if you have trouble cutting streight with the chiansaw make the grove with a parting tool then you have a guide to follow with the saw.:2tsup:

[NeilS]

... that is something I don't plan to try :no:, and definitely not before I have perfected juggling, while mono-cycling, while train surfing, by which time chainsaw swallowing may have some appeal....:D

Neil

[44Ronin]

Handsaw.....

[turnerted]

Hi
Thanks for all the suggestions .This idear certainly got the blood running hot .I will look into a tilting device to mount the chainsaw on the banjo and cut stationary . Joe the blank is mounted on a faceplate and I would have the tailstock up against the other side so it could not unscrew but I agree that to cut from the other side would be better .

[aak]

Hi
Thanks for all the suggestions .This idear certainly got the blood running hot .I will look into a tilting device to mount the chainsaw on the banjo and cut stationary . Joe the blank is mounted on a faceplate and I would have the tailstock up against the other side so it could not unscrew but I agree that to cut from the other side would be better .

Hi Ted,

When I first read your post I was horrified! Then I read the first few replies to it and thought great, there are a few sensible advice here and thought you will not persist with your idea of using the chainsaw on the lathe. So, I did not post what I thought, no need for controversy!

We, at least most of us have made some stupid decisions in our lifes, some were more dangerous then others. While I have not attempted anything as dangerous as you are attempting to do, I wish someone would have said to me each time DO NOT DO IT! It is far better to learn from someone else's misakes than from ours!

I have no idea what prompts you to persist with a very dangerous way of cutting the timber in half when there are several safe or at least much safer ways to do it. Neither I nor others can stop you doing it your way. I, like Eliza, did not need my morning coffee to wake me up on either of the two occassions I read your post.

Mate, I sincerely hope you will not end up in hospital or worse!

Regards
Andy

[Harry72]

Yep parting tool and a hand saw, you only lose 3mm of wood.

If its a round blank do not use a band saw... it can be very nasty.(370mm would need a very large saw anyway)

[NeilS]

If its a round blank do not use a band saw... it can be very nasty.(370mm would need a very large saw anyway)



Harry is right about the danger, unless you use a use a jig/skid like the one suggested by Skew (see crosscutting rounds paragraph in following link):

http://www.woodworkforums.com/showpost.php?p=865490&postcount=3

As for a 370mm round, cut from multiple sides with the bandsaw and complete the cut with bow or bucksaw. One good use of broken bandsaw blades (not me :U) if they still have plenty of edge left on them is to cut them to length to fit a deep bowsaw to complete such cuts. Re-purposed BS blades have the advantage of matching the width of the existing BS cuts.

Neil

[gb turner]

I am fairly new to the forum so I try not to say much to people that i feel have probably more knowlage than me in almost everything there is BUT I have worked in the forest industry in BC for twenty years as a tree faller and I have been hurt seriously twice by trees that were not turning in circles. If you don't want to meet your maker please put the saw away and forget you ever had one if this is the way you plan on useing it.

My suggestion to you is to find someone that knows how to sharpen a saw properly. A sharp saw should cut the blank straight if the bar is not worn-out.

By all meens use your own common sense please.

[Broda]

what about gripping the wood in a big vice or something.
i have seen something like this that Triton makes that you could use

http://www.triton.com.au/product.php?id=70

hope this helps

[RETIRED]

I don't condone using a chainsaw in this fashion.

This is more of a general thing about using the tailstock or a vice to hold the timber. It will jam the saw.

You need to hold it on one face and cut off the "waste".

[turnerted]

Hi
You may all relax now . I cut my blank in half about an hour ago with no problems .
I mounted the blank on a face plate and brought up the tail stock and using a 5mm parting tool and making two side by side cuts ,I was able to part in about 80 mm . I then made several cuts using the chain saw and rotating the blank about 180 degrees and locking it before each cut .When I got down to about 50 mm left holding , I removed the tailstock and placed a wooden wedge between the righthand side blank and the lathe bed with the thick side of the wedge toward me . This ensured that when I made the final cut , the cutoff rolled away from me .
I thank all of you who were concerned about my safety . I do have a healthy respect for chainsaws and for many years I was an acredited chainsaw operator with the bushfire brigade .It was interesting that although everone said don't do it the way I had originaly proposed ,Joe and Hughie were the only ones who gave reasons .
Ted

[RETIRED]

Can't see where Hughie replied.

[joe greiner]

Can't see where Hughie replied.

Might have been a PM.:rolleyes:
[Hard to believe hughie would have deleted it before you {might have seen} it.]

[BobL]

My mini chainsaw mill (http://www.woodworkforums.ubeaut.com.au/showthread.php?t=46980) set up will handle logs standing on end (and mallee roots and just about any awkward shape or at any angle.

[turnerted]

Hi
Sorry . Should have said . Must have ingested too much rosewood dust .
Ted