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Scratch stocks used across the grain

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xy mosian

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I am about to start a job, for me, which is likely to need a scratch stock used across the grain. The wood is going to be 'Central American Mahogany' which is twenty years dry. Now I am going to do this anyway, but I wondered if any of you chaps had done anything similar. If so have you any tips regarding the cutters edge etc.?
Thanks in advance.
xy
 

dannykaye

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basically I have to say it is not going to work. you need some sort of cutting action not a scraping IMHO
 

xy mosian

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Thanks fellas, I rather suspected that it was/is going to be difficult. I'll have to look at the Garrett Hack videos tomorrow.
Perhaps my elliptical frame will have to be circular so that I can run the moldings on some sort of lathe. Or maybe long grain sections rather than short.

xy
 

GazPal

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xy mosian":2bqcva9e said:
Thanks fellas, I rather suspected that it was/is going to be difficult. I'll have to look at the Garrett Hack videos tomorrow.
Perhaps my elliptical frame will have to be circular so that I can run the moldings on some sort of lathe. Or maybe long grain sections rather than short.

xy
If the workpiece is eliptical you can test your method on scrap, but be sure to follow grain direction whenever possible. What type of profile do you intend to form using the scratch stock?
 

devonwoody

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Oddly enough I had a similar situation last evening, I used the router table, but not a 100% success either.
 

woodbloke

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It can be done across the grain, but it's not easy as there's a big risk of tear out. A way round it is to mark the extremities of the cut with a cutting gauge - Rob
 

Pekka Huhta

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On an ellipse you can use the scraper about 80% of the time, so you don't have to re-design your work. I love elliptical designs, it would be a pity if you had to lose the shape just because of some ornaments.

End grain is no problem on scrapers. You may have to harden the fibres by applying some shellac to the wood, but it can be done. And you can always use chisels on the short distance that you can't scrape. It may not look perfectly identical but if you cut the edges with a mortice gauge with sharp cutting knifes. That way you get the edges crisp. If the scraped molding has some other sharp shapes on the profile, you can cut them as well with the mortice gauge and do the rest slowly by alternatively scraping, chiselling and, finally, sanding the molding. It is surprising how much the molding itself can vary if the edges are sharp and nice.

Some photos and ideas about end grain scraping were at

https://www.ukworkshop.co.uk/forums/post ... tml#222364

The final shape is below:




Pekka
 

xy mosian

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All good advice, thanks. Here is the section, sorry it's a bit on the large size. This is the section of the hardwood face which will be glued to the laminated core, forming the front of the rebate. My plan is for an elliptical mirror with the face grain radial, if possible. I will certainly be testing on scrap. Fortunately the Mahogany has a very tight grain, at least that is in my favour. Now the outer radii could be routered but if I am making scratch stock blades then why spoil the fun :). At the moment I am thinking of at least three scratching operations.



Thanks for your interest.
xy
 

xy mosian

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Pekka, that thread pre-dated my knowledge of this site, thanks for the link. I must admit I am beginning to wonder if am looking at a carving exercise.
xy
 

bugbear

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xy mosian":2im2b7om said:
My plan is for an elliptical mirror with the face grain radial, if possible.
Ah hah!

A cunning scheme to maximise end grain!

BugBear
 

xy mosian

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You're right BB, sad ain't I?
I am looking for something different to the standard change of grain, nice as it is, that we see on turned frames. The alternative seems to be long grain segments, as in a wheel rim, around the frame, or short grain segments. I think I can hide joints more easily with short grain segments, so bring it on. The management reserves the option to change its mind of course. :)

xy
 

GazPal

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xy mosian":39y3ljsm said:
All good advice, thanks. Here is the section, sorry it's a bit on the large size. This is the section of the hardwood face which will be glued to the laminated core, forming the front of the rebate. My plan is for an elliptical mirror with the face grain radial, if possible. I will certainly be testing on scrap. Fortunately the Mahogany has a very tight grain, at least that is in my favour. Now the outer radii could be routered but if I am making scratch stock blades then why spoil the fun :). At the moment I am thinking of at least three scratching operations.



Thanks for your interest.
xy
You've also an option to cut a separate, straight moulding in the edge of a long section of matching timber, cut it to the desired thickness (Forming a 6mm - 7mm thick moulded banding strip) and - depending on the radii involved - bend the continuous piece to conform with the perimeter of the ellipse. This eliminates end grain exposure and the only joint involved would be a scarving joint.

This also opens up possibilities for the introduction of decorative inlay between the banding strip and the main body of the frame.
 

Woodwould

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Cross-grain moulding is something I enjoy doing, but as others have said, tear out is always a possibility.

Depending on the wood, either a lubricant or a solidifier often helps. Lubricants can be anything from washing-up liquid, meths, or white spirit – or a combination. Solidifiers can be animal glue or shellac, both of which can be disolved and flushed out afterwards.

I made this cabinet a while ago with various cross-grained mouldings.
 

xy mosian

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Sorry for the tardy reply folks.
GazPal, I had thought about fabricating the frame section and may well come back to that. Thanks for your thoughts.
Woodwould, Crikey mate, that's top quality work. You have given me a belief that cross grain molding is at least possible. Do you use anything other than a 'standard' square edged scraper blade? Burrs of any sort on the edge for instance?

xy
 

Woodwould

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xy mosian":2jzo4b5s said:
Do you use anything other than a 'standard' square edged scraper blade? Burrs of any sort on the edge for instance?

xy
No, nothing special. I make my cutters from recycled saw blades which are filed and/or ground square.
 
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