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24th January 2012, 10:14 PM #1Member
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- Mar 2011
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using a router to turn a shallow concave??
Hi! I've potentially got a job coming up and thought a router may be the most efficient way of achieving consistancy. I've done a bit of a search and saw that someone had mentioned a router on a swinging arm being used to hollow large 1m diam bowls.
I will need to turn a shallow concave (300mm diam and only 5mm deep) in a 400mm square stool top (20-25mm laminated American walnut boards).
I could hand turn the concave (like a shallow bowl) but the order is for 8 and since it is such a shallow curve I think any variation would be very noticeble. Also, I need a good finished cut to reduce the amount of sanding since it's side grain and I want to avoid any hard-soft grain variation.
I was thinking of mounting a curved template to the bed on the tailstock side of the stool blank. I would then have the router base plate (or an extension of) ride along this template. The router would be orienated with end of the router bit facing the headstock.
A single pass would probably be ok given the shallow depth (5mm max at centre).
I thought of a swinging arm but given how shallow the curve is the radius may be a couple of metres.
Any thoughts...
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24th January 2012 10:14 PM # ADSGoogle Adsense Advertisement
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24th January 2012, 10:38 PM #2
How about parking the toolrest across the ways with a template attached to it and rig a depth stop to a large round nosed scraper. Doesn't seem worthwhile making anything fancier for 8 items
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24th January 2012, 10:40 PM #3Retired
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- Tooradin,Victoria,Australia
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Hmm. I don't think a router is the way to go for this one.
The problem with doing it with a router is that it tend to tear the grain on the quarter, much like turning.
If you can't hand turn it which is the way I would go, set up your compound rest to cut a taper starting at 4mm - 4.5mm deep at the centre.
Cut inwards from the rim in a straight line and (dare I say it) use 80# paper on a styrene foam* pad to sand the curve in.
*Foam fruit box type stuff.
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25th January 2012, 07:25 AM #4Been here a while
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One way I've seen of doing this is with a radial arm saw - fix the blade so it can't move front to back, then swing the blade through an arc from left to right, and it will cut a nice shallow dish shape. The only problem is the size, you're going to need a pretty big blade!
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28th January 2012, 02:08 PM #5
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29th January 2012, 07:09 PM #6Member
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- Mar 2011
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Thanks for the replies. I might try fixing a depth limiter to a scraper somehow. I'll let you know the outcome if the job comes through.
Cheers,
John.
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30th January 2012, 04:52 AM #7Member
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- Dec 2008
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- Abilene, Texas USA
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- 87
This could be modified to work. Low Cost Duplicator
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