Problem with pattern bit space between bearing and cutterhead...

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Forum topic by Vrtigo1 posted 10-30-2011 10:36 PM 904 views 0 times favorited 5 replies Add to Favorites Watch
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434 posts in 2415 days

10-30-2011 10:36 PM

I’m using a bowl and tray bit trying to make some bowls with my router. I made my own template out of 1/8” hardboard, but the problem I’m encountering is that the bearing on the bit which rides along the template has about an 1/8” gap below it before the cutterhead begins. It’s hollowing out the bowl, but I’m left with a thin piece of wood at the top of the bowl right below the template that isn’t getting trimmed. If my template was thicker this wouldn’t be a problem, but I’ve already got about 2 hours in making this template so I’d rather not make another one.

Seems like the easiest solution at this point would be to use a really short bottom bearing flush trim bit to remove that bit of untrimmed wood, but I don’t have a short enough bit so would need to go to home depot and hope they sell them.

I’m wondering if there’s a simpler solution staring me in the face that I’m not seeing…

5 replies so far

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404 - Not Found

2544 posts in 2392 days

#1 posted 10-31-2011 02:18 AM

How about making a new template from 3/8 or 1/2” mdf using your hardboard template and a bearing guided trimming bit. Rough it out with a jigsaw and clean it up with the router.
If that won’t work, a shallow top bearing guided bit would do it and would have lots of uses in the workshop – cutting housing joints etc.

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13524 posts in 2764 days

#2 posted 10-31-2011 02:23 AM

maybe round over the top
with a 1/8th bit
or a chamfer bit
it will ride against the side of the bowl
without the template

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

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8523 posts in 3072 days

#3 posted 10-31-2011 02:35 AM

Take another panel of hardboard – cut an opening in it that is slightly larger than the template (does not have to be precise) and put it between your template and your parts to be routed – lifting the bit ~1/8” higher so that you won’t get that lip on your parts.

next time – double up the hardboard for templates of this sort.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

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4827 posts in 2237 days

#4 posted 10-31-2011 07:09 PM

Use your template to recut another template out of 1/2” or 3/4” mdf.
I am surprised to hear the bearing is elevated like that. I have about 6 pattern / flush trim bits from various manufacturers, and they all have bearings very close to the cutter.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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434 posts in 2415 days

#5 posted 11-01-2011 04:26 AM

Thanks all for the suggestions, all very good options. I like the idea of using a pattern bit to make a thicker template out of MDF.

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