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Forum topic by Cunning posted 03-04-2020 01:42 AM 601 views 0 times favorited 13 replies Add to Favorites Watch
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Cunning

2 posts in 130 days


03-04-2020 01:42 AM

Topic tags/keywords: question pine router shaping

I do not have a CNC router but was wondering if there is an inexpensive one out there that can handle what I want to do.

I have several squares that I need to make out of pine or Dfir. Stock is 1.5” thick actual size. Each square needs to be about 5-6” across and needs to have a 1 1/4”-1 1/2” roundover on each edge on one face. I was wondering if there is a bit that can do this in one or two passes . I would like to cut these pieces out of longer boards (up to 8’), and clamp (or vacuum) the 8’ piece onto the cnc router table, then use the router to not only cut the square shape but also cut the roundover on each edge at the same time. My thinking is that i would not cut these squares quite through, then take the 8’ board and run through a thickness planer to take off the little bit that is left on the bottom and separate each square.

My questions are;
Is this do-able,
What kind of price for a cnc with such capabilities.
How much time it would take to cut each piece?

Can anyone help?


13 replies so far

View John Smith's profile

John Smith

2440 posts in 938 days


#1 posted 03-04-2020 12:27 PM

Cunning – how many of these squares do you want to make ?
and, what will they be used for? (will they be clear-coated or painted).
if they will be painted, there are other options available without
buying a CNC just for this project. what kind of tools do you have access to ?

drop over to our sister site: https://www.routerforums.com/
and ask the same question. that website is specifically for CNC router enthusiasts.

Edit: I can’t wrap my mind around the part where you want to “run the 8’ board
through a thickness planer to take off the little bit that is left on the bottom and
separate each square” I am thinking that has disaster written all over it.
there must be an easier and safer way to do this part.

.

-- there is no educational alternative to having a front row seat in the School of Hard Knocks. --

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John Smith

2440 posts in 938 days


#2 posted 03-06-2020 12:45 PM

Bump – I’m still interested in this project.

.

.

-- there is no educational alternative to having a front row seat in the School of Hard Knocks. --

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Madmark2

1380 posts in 1364 days


#3 posted 03-06-2020 05:52 PM

How did you figure on indexing the 2×8? Tolerances will be tight or you only cut three sides per pass.

How many of these do you need?

An 1-1/2” deep cut with a round over is a bit much to hog out even with a CNC.

It would make more sense to cut the 2×8 into squares on a chop saw (using a stop) and then just round the edges with the CNC.

Given the size of the pieces and the time to load and unload the part from the jig I’d put odds on that a man with a table router would be as fast if not faster and certainly less costly.

-- The hump with the stump and the pump!

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John Smith

2440 posts in 938 days


#4 posted 03-06-2020 08:17 PM

Mark – this is why I asked the same questions.
I have a 1-1/8” (maybe 1-1/4”r) roundover bearing bit that I have used
several times on redwood and High Density Urethane sign foam (HDU)
with good results. a larger, 1-1/4 or 1-1/2” radius on hard pine
would be very on the tool and end grain. and, may be beyond
the tool’s parameters for a safe and efficient project.
if those blocks are to be painted, like for an accent wall, I would use
18 pound High Density Urethane which is just as hard and durable as soft pine.
and much, much safer and easier on everything. and no end grain to tear out.
(and a whole lot easier to prime and paint).
[still waiting on the O/P to come back with clarification on his project].

.

-- there is no educational alternative to having a front row seat in the School of Hard Knocks. --

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Madmark2

1380 posts in 1364 days


#5 posted 03-06-2020 08:56 PM

Yeah, and that bearing is going to be hard to shove thru the 2×8.

Got a bit with that profile and cuts to the tip w/o bearing?

I generally make two passes, one a hogging pass and the 2nd cleanup. Of course this doubles the run time by hand or CNC.

-- The hump with the stump and the pump!

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John Smith

2440 posts in 938 days


#6 posted 03-06-2020 09:32 PM


Yeah, and that bearing is going to be hard to shove thru the 2×8.
- Madmark2

yeah, the bearing bit is to finish the pre-cut blocks by hand.
I think what the O/P is envisioning is a non-bearing bit that will cut all the way
down to almost the bottom of the board less than 1/8” so he can cut the “flashing”
off in the thickness planer. that is where I see the biggest problem to be.
IF he can find a bit that will do that, I would screw the 2×6 to a piece of sacrificial
board and cut all the way through on the final pass. (yes, it will take several passes).
to do this in a CNC, he would have to have the bit custom made for this project. (which is doable).

.

-- there is no educational alternative to having a front row seat in the School of Hard Knocks. --

View DS's profile

DS

3503 posts in 3196 days


#7 posted 03-11-2020 01:53 PM

The technique the OP is describing is called “Onion Skinning”.

When we do it, we wouldn’t put the pieces through a thickness planer as, when they break the part loose, it can get squirrely in the planer.
We typically would just use a small flush trim router on the back side to break the parts loose.

“Tabbing” is also an option here.

A small cnc machine might have trouble with the large radius tool you want to use. You would need about 3hp minimum and slow the rpm to 10,000 or so to get a good cut. Also, they make plunge roundover versions of these bits with no bearing, however most commonly available versions have an elongated flat on the plunge which can be cut shorter by a sharpening service.

Magnate offers a good line of bits with this type of routing in mind, intended for the Legacy Ornamental Mill and the new Legacy CNC lineup they have. They are sold on Amazon.

(Just FYI, our machine is a big beast and cost $110K new.)

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

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DS

3503 posts in 3196 days


#8 posted 03-11-2020 03:30 PM

Another onion skin example

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

View Cunning's profile

Cunning

2 posts in 130 days


#9 posted 03-12-2020 08:51 PM

Sorry to the guys who answered me I have been away from my computer. Thanks for the replies. The project is making several hundred pieces out of the pine or Dfir that are about 5” across and flat on the bottom and the topside is roundovered at about 1 1/4” radius. Pieces are 1.5” thick and will be finished with something clear like varathane. Pieces are being used under plant pots as coasters, flat face on the bottom. It has been difficult to make these squares but I’ve had a request for round pieces, which will be more challenging. I have a router table with a 1 1/4” roundover bit and made a jig to control the piece but it is too sketchy (ie unsafe) and tore a lot of the grain. I talked to a cnc producer and he said the pieces would cost about $10 each to purchase them. So I wanted to see if I could introduce myself to cnc routers by making these pieces. The onion skinning technique was what I was trying to explain with routering the pieces almost all the way through then using a thickness planer to take off the last little bottom bit. The final finish needs to be equal to about 100 grit sandpaper so I am thinking that even with a cnc I will still need to sand these pieces, which is one thing I was trying to get away from. It also sounds like I would need a pretty high end cnc to make these efficiently. I will check out the bits and ideas you have answered with but any help would be appreciated.

View DS's profile

DS

3503 posts in 3196 days


#10 posted 03-12-2020 09:25 PM

It seems to me that what you need is a good jig on a router table to make it not a sketchy setup.

This could actually be faster than the processes needed to make them on a CNC.

Think, lazy susan bearings and a platform to spin your part taking a few steps to plunge all the way through.

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

View John Smith's profile

John Smith

2440 posts in 938 days


#11 posted 03-13-2020 11:18 AM

Cunning – drop over to Router Forums which is the sister site of this one.
it is a forum for CNC and Hand-Held router enthusiasts that love projects like this.
if you ask this question in other forums, it would help a LOT if you go into some detail
as to what you have tried already, and what worked and what didn’t.
when you give as much information as possible in the first paragraph, it cuts the “speculation”
way down to receiving actual useful advice.
like your 2nd post: if you had posted all that information first, it would have been most helpful.
the Admin and Staff are the same on Router Forums as it is here.
all the best,
John

.

-- there is no educational alternative to having a front row seat in the School of Hard Knocks. --

View DS's profile

DS

3503 posts in 3196 days


#12 posted 03-17-2020 02:21 PM

To cut cleanly without tearout, a CNC program would usually cut with a “climb” cut.
This is opposite of how you would use a router table or hand held router.
To attempt this by hand is very dangerous as the router bit would attempt to climb out of the work piece and throw it.
The work piece would need to be secured firmly in a jig that controlled all movement of the piece.

A rotary index table like ones used in a vertical mill would give such control that you could do a climb cut without needing a CNC machine. Mount this on a router table and there you go.

If you know a little programming, you could add a couple of stepper motors, a basic controller and a bit of software and you could automate the process. This would require a custom router lift with a stepper as well.

Such a specialized machine would be efficient and cost effective, but would make only the one thing.
Food for thought.

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

View Underdog's profile

Underdog

1510 posts in 2811 days


#13 posted 03-17-2020 02:51 PM

I’m not sure “Inexpensive” and “Big Router Bit” should go in the same sentence… LOL!

However you do it I’d make several roughing passes with a 1/2 diameter bit to get some of the material out of the way.

-- Jim, Georgia, USA

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