Challenge

[tim_m]

Hello
I have a customer that wants me to reproduce some reeded picture frame molding. I've tried millwizard and the shopbot extruder and the best I can do is about 1 1/2 hours to cut 4ft. The stock is poplar 1.4"x4". I'm using a 3/64 tapered ball end mill to get in as far as I can btween the reeds.

4724


4723 (16.5 k)

[Brady Watson]

Tim,
I cannot get any meaningful information from your attached DXF. Please attach a profile that works. Test it by importing it into PartWizard.

What machine are you running? You should be able to carve that rather quickly on an Alpha, although it's the small bit that is going to kill you for time...and there's not much you can do about that. If the customer needs a large number of these pieces, it's cheaper and faster in this case, to get custom knives ground and run them thru a molder.

-B

[tim_m]

I'll try again. For some reason the file ext. was changed. I was able to use save as and change the extension back to .dxf
I'm running an alpha @ 4"/sec with a .01" step over.
My customer is an artist that just wants to frame a couple of his paintings per year.


4725 (13.0 k)

[tim_m]

OOPS!it looks like the same thing happened.
the ext. needs to be changed to dxf when you save it. any ideas about what's going on there?

[Brady Watson]

Tim,
You are going to be hard pressed to improve on your time of 1.5hrs with that file. You really have to run that 3/64" bit over the entire model to get the detail that you need. If the customer only needs a few strips, just set them up to run and go do something else. For 3D I charge by the square foot, not by time.

The .01 stepover is a little coarse for this design, and you might want to tighten it up some, even though it will take more time to cut the piece. If I were doing it, I would machine the entire model with a 1/4" ball (doing a roughout 1st, tricking MW by telling it that it was a square end mill), followed up with a 3D TP using the same 1/4" ball, with a 20% stepover running at 8 IPS. After that, run the 3/64" bit as fast as it could stand. With a good roughing pass and coarse stepping 3D TP before using a smaller tool, you can really get the finish pass to cook. I've cut @ 7 IPS with a 1/32" ball recently without breakage...your mileage may vary.

Some prescribe to the notion that a roughing pass is a waste of time...it isn't. It allows you to run your finish pass faster, with a greatly reduced risk of tool breakage ~ that by the way, eliminates the need for cu$tom bit$ and things like that.

-B

[tim_m]

thanks Brady
I have beenn using just one roughing pass with the 1/4" ball. What is 3D TP? Sorry I'm still green. It looks like I could cut my time in half if I bump up my finish cut speed. What kind of stepover would you recomend?

[rick_woodward]

Well, A reeded strip immediately makes me think of using a plunge roundover bit.....After a rough pass with a 1.4 inch bit.But a custom knife is the best way. If doing it on the shopbot is the only answer and this shape isnt feasible, i'd talk to him about changing it. Maybe a reeded low crown shape. Tilt the blade on your tablesaw and rip them at an angle for a tilted angle on the assembled frame. Tim, 3D TP is a 3d Tool Path

[Brady Watson]

Rick & Tim,
I was going to suggest a plunge roundover bit at 1st glance, but after examining the design, it appears that the roundover won't be able to get into some of the spots, or if it does, it will distort the design...still requiring a 3D tool to clean it up.

No doubt about it, it's a challenging design to cut fast...As the great Ron Popeil once said, "Set it & forget it...It's just that easy!"...Set up the machine and go do something else. While this job may take many hours to machine, the total linear feet is small...AND you never know what else will come down the pike after you do this job....trust me. People don't like being told no, or getting anything other than what they want...If you can deliver that, you won't be forgotten.

-B

[tim_m]

Brady
I totaly agree with finding a way to give the customer what they want. And I'ld do this job just for the challenge. I'm going to try out a test piece with a faster finish pass.
thanks everyone. I'll try to post pictures when it's done

[gpari]

How about a plunge roundover bit, but with the part on an indexer?

Gabe

[cip]

Tim, Have you thought about getting the molding run on a molder? I tried to run molding on my Bot and gave up because of the time factor and bought a molder. I run lots of molding mostly radius but straight is no problem.

Mike

[jhicks]

I agree with Mike, YES you can hopefully find a way and maybe the plunge roundover would work assuming all are equal sizes and radius or more bit changes lie ahead.
Even if you do figure it out, lots of time compared to profiling on a moulder.
A set of knives in the hands of anyone with a Woodmaster or William & Hussy would cost perhaps $200.00 or so and profiles would run is approximately 8'/ minute or faster for the complete length and be done. Plus you can run it over and over with quick set up and no additional expense.
Bots are great but for some jobs there are more efficient methods out there.

[gpari]

I'm not sure a molder would be able to make the profile exactly as it is shown either, it looks to have some undercutting. Although, having knives made would be much faster, cheaper, and would probably work better in the long run. But, watching a molder run is not nearly as fun


Gabe

[tim_m]

i agree that having knives cut is maybe the way to go. i have given my customer a quote for doing it on the bot and the number for someone to mill it for him. he's going to check it out and get back to me. either way he's happy. i have run into this alot already. people coming to me with jobs that are better suited for other tools. but, if i can give them information that gets them what they want they seem to come back.
thanks for all the input.