Pits in my turning

[A.Turner]

Hello,

I've dried some logs I collected from a work colleague and cut them into smaller pieces. When I turn them I notice large pits. What I also notice is that in the direction it was cut the surface is smooth, but the other direction it is rough, examples:

http://2.bp.blogspot.com/-c-WooFXti...WD0/XC5N7Nf3Gd8/s1600/2015-08-17+20.51.53.jpg
http://2.bp.blogspot.com/-sdwfuLe_p...WDw/Y6iW52VwozY/s1600/2015-08-17+20.52.10.jpg
http://4.bp.blogspot.com/-iN9W4O81o...WD8/pDQ6XdtJ_5E/s1600/2015-08-17+20.52.32.jpg

I don't know what kind of wood it is but I've gotten similar, albeit smaller, on pine as well. It's as if bits of wood are being ripped out yet it only occurs in patches. The tools are sharp and I cut slowly.

What is causing this?

 

[NickWelford]

Soft wood plus end grain, plus, how sharp are your tools, really? Take the smallest of cuts.

 

[A.Turner]

Just read this : http://www.turningtools.co.uk/wtintro/grain/grain.html. Makes sense but I can't actually see the grain in the wood. I suppose, logically, if the sides are the end grain then the grain must be flowing along the bed in which case on the surface I am cutting across the grain.

So I need to turn my wood like this: https://picasaweb.google.com/100006047484245559277/WoodTurning#6184307406010345618?

As I generally only have access to logs destined for somebodies wood burner it'd require chucking away a lot of wood.

 

[Dave Brookes]

No, you don't necessarily have to turn your wood like that; sharp tools and perhaps a faster spindle speed should be able to overcome the problem. However, if the wood is a bit soft, you could use some wood hardener before the final cut and sanding (providing of course that the grain tear-out is not too deep).
The Toolpost in Didcot sell a relly good wood hardener which works! Also, it does not tend to discolour the wood.

Dave

 

[A.Turner]

The example pieces were cut at 4000RPM, the tools are as sharp as I can do on my basic grinder. My next purchase will be a proper sharpening system, but they are inexplicably expensive. I wouldn't know if the wood is soft or not, where the pits are feels like plastic bristles though. It reminds me a great deal of a dead sunflower head with all the seeds missing.

 

[Dave Brookes]

If you cannot resolve the issue then feel free to come to our next Hands-On club meeting, Didcot & District Woodturners &.30pm on Wednesday 26th August. I know its a fair way, but our August meeting is always held at the Toolpost and there will be plenty of assistance and suggestions to help you.

Dave

 

[Paul.J]

Looks like the wood has spalted but now gone too far so will be difficult to get a good finish on unless you want to spend time trying to harden it.

 

[A.Turner]

Didcot is indeed a bit of a trek, but thanks for the offer.

There is only one club in my locality, they meet once a month and every other meet is a demo. Not very helpful when you need mentoring.

Spalted. I get the wood for free so I use whatever I am given and am grateful for it. The cost of ready dried wood is prohibitive for a minor hobby though I have bought a couple of pine balustrades from B&Q before.

I shall try another piece and cut sliver by sliver. I tend to cut fast because a) I can and b) my free time is very limited.

 

[NickWelford]

A bit of one to one hands on tuition is worth considering.

 

[pennardesign]

Hello,

I've dried some logs I collected from a work colleague and cut them into smaller pieces. When I turn them I notice large pits. What I also notice is that in the direction it was cut the surface is smooth, but the other direction it is rough, examples:

http://2.bp.blogspot.com/-c-WooFXti...WD0/XC5N7Nf3Gd8/s1600/2015-08-17+20.51.53.jpg
http://2.bp.blogspot.com/-sdwfuLe_p...WDw/Y6iW52VwozY/s1600/2015-08-17+20.52.10.jpg
http://4.bp.blogspot.com/-iN9W4O81o...WD8/pDQ6XdtJ_5E/s1600/2015-08-17+20.52.32.jpg

I don't know what kind of wood it is but I've gotten similar, albeit smaller, on pine as well. It's as if bits of wood are being ripped out yet it only occurs in patches. The tools are sharp and I cut slowly.

What is causing this?

This used to plague me, I now keep my tools super sharp and only take a few cuts with the scraper before I sharpen it (leaving the burr on the tool edge) hope this helps. I also seal end grain before I sand it with a sanding sealer.

 

[A.Turner]

To clarify my cutting speed! I cut shallow but fast, hot knife trough butter.

I use the wheel that came with my grinder and I suspect it is quite rough and will do little for tool longevity. I see Axminster do a frame I can stick on my grinder http://www.axminster.co.uk/storme-woodturner-s-sharpening-system, that be an affordable solution, along with a better wheel.

 

[chipmunk]

I think it's also probably to do with the angle your cutting edge is to the timber during the cut and whether the bevel is rubbing.
I suspect you are not slicing the wood fibres but presenting the tool more or less square-on and the bevel isn't anywhere near rubbing.

Try using a skew-type planing cut with a rubbing bevel and if your cutting edge is sharp enough I think you should eliminate that tear-out.

If not then it's the wood - burn it or give it away and get yourself something that'll cut better.
HTH
Jon

 

[NickWelford]

The wheel that comes with the grinder is quite unsuitable for sharpening chisels. You need a white or red wheel

 

[chipmunk]

The wheel that comes with the grinder is quite unsuitable for sharpening chisels. You need a white or red wheel

Well I agree that red or white wheels are better but I'm not sure that is strictly true. Provided the wheel is well dressed and unglazed, and a cheap devil stone will do that job, and it is used lightly and the tool not allowed to get too hot, even a grey wheel will do the job.

Jon

 

[NickWelford]

The wheel that comes with the grinder is quite unsuitable for sharpening chisels. You need a white or red wheel

Well I agree that red or white wheels are better but I'm not sure that is strictly true. Provided the wheel is well dressed and unglazed, and a cheap devil stone will do that job, and it is used lightly and the tool not allowed to get too hot, even a grey wheel will do the job.

Jon

But it generally leaves the edge 'ragged'

 

[chipmunk]

But it generally leaves the edge 'ragged'

Sorry Nick, but doesn't that depend on the grit of the wheel? Not all grey wheels are coarse IME.

 

[Paul Hannaby]

Unless I missed something, you didn't mention which tool you used for cutting those pieces of wood. Which was it?

Regarding cutting with the grain, that would entail cutting from the wider diameter to the smaller diameter on spindle work where the grain is running parallel to the lathe bed (as it is with your examples).

 

[A.Turner]

3/8" spindle gouge. It's Axminsters own http://www.axminster.co.uk/axminster-hss-woodturning-tools-set

 

[Mark Hancock]

To me it looks like a combination of factors, some of which have already been mentioned:
1. quality of timber
2. sharpness of tool
3. speed of lathe - 4000 rpm is extremely fast for a wood turning lathe?
4. grind on tool
5. angle of presentation of tool
6. feed rate of tool
7. grain orientation

I would strongly suggest you look into getting some tuition. It saves a lot of frustration and time in the long run.

 

[finneyb]

Axminster Nuneaton are offering free sharpening during August http://www.axminster.co.uk/stores/nuneaton/#
Check the limitations.

That will tell you if its the tools causing the problem

Brian