As a newbee to turning I have just turned my first bowl using a Sycamore blank and the bowl form looks fine, but I'm having trouble removing the tool marks. Started with 80 grit then 120,180, 400 and 600 and at first using the 80 the marks seemed to have gone but by the time I reach the 600 they are back! The bowl feels perfectly smooth but the tiny white rings are still there, what am I doing wrong? I am hand sanding not power.
Sanding out tooling marks
- Thread starter malc75
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Spindle
Established Member
Hi
Its a little difficult to comment without seeing a photo but here goes:
My guess is that you have torn the grain by either letting your tools get a little blunt or by accidently taking too heavy a cut. The coarser grit will flatten out the undulations in the surface so as it feels and looks smooth but as you move on to the finer grits they reveal the areas of torn grain which will become more obvious as you move on to finer grits.
Are the marks more prominent on end grain?
Regards Mick
Its a little difficult to comment without seeing a photo but here goes:
My guess is that you have torn the grain by either letting your tools get a little blunt or by accidently taking too heavy a cut. The coarser grit will flatten out the undulations in the surface so as it feels and looks smooth but as you move on to the finer grits they reveal the areas of torn grain which will become more obvious as you move on to finer grits.
Are the marks more prominent on end grain?
Regards Mick
Scratch marks can be difficult to see, one thing I have found in my colour work is that nothing makes a hidden scratch show up as well as a bit of colour! Hence I take extra care to try and make certain they are gone before I do any colouring. How does this help you though eh?
Well, you could try a slight variation on the theme, get a little dirty water, not to much, and smear it across the work, any bad scratches will show up easily, allowing you to sand them away, once you have got rid of the worst (each grade will always have a few slightly deeper ones, move onto the next grade, byt the time you get to the 240 grit, if there are no big marks, you can abandon looking for them and go 320, 400. I don't see any need to go finer as a sanding sealer will will allow you to fill and cut back to a very polished finish from 400.
Just an idea, see how it works!
Well, you could try a slight variation on the theme, get a little dirty water, not to much, and smear it across the work, any bad scratches will show up easily, allowing you to sand them away, once you have got rid of the worst (each grade will always have a few slightly deeper ones, move onto the next grade, byt the time you get to the 240 grit, if there are no big marks, you can abandon looking for them and go 320, 400. I don't see any need to go finer as a sanding sealer will will allow you to fill and cut back to a very polished finish from 400.
Just an idea, see how it works!
chipmunk
Established Member
Hi Malc,
A couple of things spring to mind.
When you're sanding keep the lathe speed relatively slow and keep the paper moving. Also make sure it's a new piece of paper - keep your tools sharp :wink:
The other thing is that there is a big jump in grits from 180 to 400. All of your tool marks should be gone with the 80 grit. All of the higher grits are just focussed on removing the marks of the previous grit. Sanding out 180 grit marks with 400 grit paper may take a while. Try to find some 240 and 320 grits.
HTH
Jon
A couple of things spring to mind.
When you're sanding keep the lathe speed relatively slow and keep the paper moving. Also make sure it's a new piece of paper - keep your tools sharp :wink:
The other thing is that there is a big jump in grits from 180 to 400. All of your tool marks should be gone with the 80 grit. All of the higher grits are just focussed on removing the marks of the previous grit. Sanding out 180 grit marks with 400 grit paper may take a while. Try to find some 240 and 320 grits.
HTH
Jon
CHJ
Established Member
Sounds to me you have bruised/torn grain marks, these can be 2-3mm deep if caused by none too sharp tools in some woods, softer wood like sycamore can be quite prone to them.
In future if using a similar specimen of wood try soaking the surface in sanding sealer prior to the last few tool passes or just plain water to swell and support the fibres and provide lubrication.
Wet shave the wood
Some times you will come across a piece of wood with growth stress lines running through it across the grain pattern that look similar to torn grain damage, only after you have chased it through several millimetres does it dawn on you that you can't remove them.
In future if using a similar specimen of wood try soaking the surface in sanding sealer prior to the last few tool passes or just plain water to swell and support the fibres and provide lubrication.
Wet shave the wood
Some times you will come across a piece of wood with growth stress lines running through it across the grain pattern that look similar to torn grain damage, only after you have chased it through several millimetres does it dawn on you that you can't remove them.
Brianp
Established Member
CHJ":6dth76sx said:
What's a soak - a couple of blasts from a triggerspray type bottle or leaving the piece in a basin fully submerged? I've noticed this a lot with sycamore as you suggested (just come into some greener timber for the first time in ages!) and thought originally it was either tool sharpness (it wasn't!) or cut direction (which it was, a little!).
CHJ
Established Member
Just brush on a coating and leave a few of minutes for fibres to swell.
Mark Hancock
Established Member
Good advice above.
The thought that sprung to me was that you haven't soften the bevel heel on your gouge. Sycamore is very prone to bruising and roughly removing the sharp heel of the bevel caused by hollow grinding reduces this.
The thought that sprung to me was that you haven't soften the bevel heel on your gouge. Sycamore is very prone to bruising and roughly removing the sharp heel of the bevel caused by hollow grinding reduces this.
Richard Findley
Established Member
I agree with Mark. What you describe sounds more like bruising of the wood rather than torn grain. You have basically crushed the wood on a fairly microscopic level but it shows up as pale rings which you will never sand out. The answer is that to need a lighter touch. By removing the heel as Mark says, it will help massively. Make sure your tools are sharp too as this reduces the need to add too much pressure. Practice turning with a lighter touch. If your hands are hurting at the end you are doing it wrong! If you are going to put pressure anywhere put it tool to tool rest rather than tool to wood. No matter what you are making, too much pressure on the wood is a bad thing.
Hth
Richard
Hth
Richard
