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Grandma's Picture Frame #2: A first go at the Insert

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Blog entry by spunwood posted 02-12-2011 03:58 PM 1024 reads 0 times favorited 7 comments Add to Favorites Watch
« Part 1: Thinking through the Design & Dimensions Part 2 of Grandma's Picture Frame series Part 3: Zero Clearance Take 2: Using a Molding Head on the Table Saw, Safety and Other Thoughts »


“This molding cutter will not fit my insert for the table saw,” I says to me. So I says, “Let’s make a new one.”


“Use some MDF and trace the Zero Clearance Insert you bought from Lee Craft,” says I to me. “yes, and good folk they were.”


“Trace the thickness needed” says I.


Okay, enough of that weird self talk. Time for the coping saw, having ripped MDF to thickness.


Trace the parts of the old ZCI so that it will fit into the table saw. These parts will need to be drilled out. Originally, I was going to grind them out, but having taken a break for work at UPS, I came up with using my forstener bits instead. Absolutely amazing how time away from something allows the gift of insight to operate.


Yup, needs some drilling & a bit of grinding to fit in.


SAFETY FIRST!


This is what an old drill press looks like!


An adjustable screw to hold it tight when inserted


We have a fit, though it is a bit sloppy at the end, and I drilled the finger hold on the wrong side, so I drilled a second one.


Okay, now I was a bit sloppy using the 1 1/4” bit to drill the clearance hole, but it fit and raising the spinning blade slowly showed that it was just about spot on.


A profile.


A thin wall on the top section


Disasterous results, blow out. It was all going so well and then my finger felt on ouch like being hit with a little bat, while a big bang/thwack sound happened.


blow out


The insert destroyed…the cutter head is blue because I was using chalk to help drill out the hole for it.


Maybe some runners for support next time?

Okay, so I ran the pine wood through the cutter slowly, and raised it bit by bit on each pass. As the blade got higher, there was more chatter on the piece, and at one point I was it move a bit. I should have used my feather board which would have made this safer and easier. But still, why did this happen?
A. Wall on the wood too thin?
B. The knot?
C. The wiggle I saw earlier in the wood?
D. Dull cutter?
E. Bad insert?
F. Raising the blade too much at once and taking to big a bite?
G. Other thoughts?

Love to have some folks help and advice here on what happened and on how to prevent the blow out and strengthen the insert. The last picture is my next plan, unless there are other suggestions.

Thanks,
Brandon

-- I came, I was conquered, I was born again. ἵνα ὦσιν ἓν



7 comments so far

View spunwood's profile

spunwood

1194 posts in 1555 days


#1 posted 02-12-2011 04:37 PM

Need help here….any thoughts?

-- I came, I was conquered, I was born again. ἵνα ὦσιν ἓν

View 489tad's profile

489tad

2443 posts in 1730 days


#2 posted 02-12-2011 06:01 PM

I’ve never used a molding head before. I would try feather boards to hold the molding in place. Down and to the fence. I hope this helps.

-- Dan, Naperville IL, I.G.N.

View KylesWoodworking's profile

KylesWoodworking

280 posts in 1412 days


#3 posted 02-12-2011 07:08 PM

I’m thinking it happened because the knot might have been a little loose, has you can see the blow out happened with the grain and in the only spot with a knot.

-- http://www.kyleswoodworking.com http://www.facebook.com/kyleswoodworking

View Jack_T's profile

Jack_T

621 posts in 1750 days


#4 posted 02-13-2011 12:18 AM

I have to agree that the knot played a major roll in this event. Additionally, I think that your choice of material for the throat plate contributed to the problem. While MDF is flat and stable it has no structural strength. I would make the next throat plate out of Baltic Birch plywood. And of course use clear stock.

Good luck.

-- Jack T, John 3:16 "For God so loved the world that he gave his only Son, so that everyone who believes in him might not perish but might have eternal life."

View HerbC's profile

HerbC

1200 posts in 1578 days


#5 posted 02-13-2011 05:03 AM

I vote for all the above…

Be Careful!

Herb

-- Herb, Florida - Here's why I close most messages with "Be Careful!" http://lumberjocks.com/HerbC/blog/17090

View spunwood's profile

spunwood

1194 posts in 1555 days


#6 posted 02-13-2011 05:48 AM

Thanks Herb. How did you cut the cove in the frame you posted?

-- I came, I was conquered, I was born again. ἵνα ὦσιν ἓν

View EEngineer's profile

EEngineer

903 posts in 2332 days


#7 posted 02-13-2011 06:12 PM

I only ever used the molding head in my table saw once. I don’t mind telling you the damned thing scared me so I took extra precautions.

I didn’t use a zero-clearance insert – the previous owner of my saw had made an aluminum insert with almost 1/8” clearance on the sides and a slot long enough to accomodate the entire molding head. But he had set it up so that it just laid in the cutout for the insert. I didn’t like that and spent some time making two spring clips that held the insert securely – one at each end. I made two featherboards – one held the piece down against the table securely and the second held it against the fence. I reasoned that kickback shouldn’t be a problem since the featherboards wouldn’t allow it – any force trying to push the workpiece backwards tightens them up. Try it; you cannot pull work backwards through a featherboard.

I used this setup to mill about 60-70 feet of 3/4” square oak to edge plywood. I didn’t take nearly the amount of material off that you did – only about 1/4” deep at the deepest part of the profile – so I did it all in one pass. I set it all up, ran about 6-7 10 feet pieces of oak through and didn’t have one problem. Knots and splits didn’t cause any problems. Running all the pieces through took about 1/10 the time it took to set everything up. With me pushing and my son pulling neither one of us got our hands within 3 feet of the whirling flesh-eating parts.

Take your time and jig everything up to be as accident-proof as possible.

-- "Find out what you cannot do and then go do it!"

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