Cutting shallow, wide slot in hardwood

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Well, kinda'! The idea was brought up but dismissed due to the fact that the slot has to be indexed to one end of the block. The tolerance is +/- 1/16" and if the block is but in the brush machine the wrong way, and the block was over or undersized, by even the 1/16", the pattern would interfere with the mounting holes. The clamps on the brush machine leave a witness mark that orients it in all the rest of the operations. However, I intend to revisit it now that you bring it up. If the Amish can mark the orientation, it'll work. Good idea, thanks!
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interfere
You might be able to facilitate this with your Amish vendor by offering to supply him with a jig of some sort. +- 1/16" is a whopping big tolerance, The craftsmanship of the Amish wood workers ought to be able to give you at least +- 1/32".
--

__
Roger Shoaf

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Tom Gardner (in VnTSg.6816$ snipped-for-privacy@newssvr12.news.prodigy.com) said:
| I need the best, cheapest way to cut a 1-1/2" wide by 3/64" deep | slot across a KD Beech block that is 2-1/4" wide. I need to do at | least 2,000/day. I already do this but I won't say how as not to | influence you. We are trying to come up with a better, faster | cheaper way.
Lots of ways to skin this cat. A 1-1/2"x3/64" +/-0.002" is easy and 14.4 sec/block (28,800 sec per 8-hour shift divided by 2000 blocks) is actually pretty slow.
The limiting factors appear to be [1] ability to cool the cutting tool and [2] material handling ability.
[1] isn't a big problem; but the method used will depend on [3] below. [2] is a larger issue - material handling might be much simplified and labor content minimized if the tooling solution inputs boards, and outputs slotted blocks.
The big questions are:
[3] How many of these blocks would you really like to produce in an 8-hour shift/day? I think that 25,000 blocks/workcenter/shift isn't an unreasonable target.
[4] What is the value of production volume (IOW, how much does it make sense to spend to achieve your production target)? "As cheap as possible" is not an answer to this question.
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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said:

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said:

I do it now with a 3 hp router swinging a 1.5" bit. The block fits in a sliding jig on linear bearings. The operator slides the jig across the bit and the block drops in a barrel. It takes about 4-5 seconds. Not too bad, but I'm worried about repetitive motion injuries and the routers only last 4 months.
My production requirements are only 800 per day but I can only dedicate so many man-hours so I need 300 per hour. Cycle time has to include material handling and pee breaks.
My biggest concern is the possibility of repetitive motion injury so, I'd rather spend the money to automate rather than taking the chance of somebody getting hurt.
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Tom Gardner (in mNpTg.391$ snipped-for-privacy@newssvr11.news.prodigy.com) said:
[ Paragraphs reordered ]
| My production requirements are only 800 per day but I can only | dedicate so many man-hours so I need 300 per hour. Cycle time has | to include material handling and pee breaks.
Ok - this essential info was missing - and is necessary to have a starting point.
| I do it now with a 3 hp router swinging a 1.5" bit. The block fits | in a sliding jig on linear bearings. The operator slides the jig | across the bit and the block drops in a barrel. It takes about 4-5 | seconds. Not too bad, but I'm worried about repetitive motion | injuries and the routers only last 4 months.
I suggest hitting E-Bay until you find a good price on a 5-10 hp industrial spindle and a VFD. If the spindle hasn't been abused, it should last a very long time. I use a 5 hp Colombo spindle and Delta (not the tool co) VFD for CNC routing and expect that they'll outlast me.
It would not be difficult to move your sliding jig with one or a pair of micro-steppers and set up the jig to clamp while in motion and release at extremes of movement. That would allow the operator to drop the block into the jig and press a pair of buttons (one for each hand), then reach for the next block while the cut is being made. You should be able to feed the block past the cutter at 3-4 in/sec (180-240 ft/min). Once the cut block has been dropped, the jig can be retrieved at a still higher speed. You'd need a PC (an old, recycled 386 would probably do) and a stepper controller to drive the motors. Using steppers makes it easy to control feed speed and acceleration/deceleration of the fixture.
If you follow the link below, you can see what the controller would look like. Your machine, of course, would only be a single-axis machine and only 1/3 as complex as the JBot shown on the web page.
| My biggest concern is the possibility of repetitive motion injury | so, I'd rather spend the money to automate rather than taking the | chance of somebody getting hurt.
Well, the operator will need to move - and the movements will be repetitive... unless you set up a system to pick blocks off a pallet or out of a box. :-)
Actually, I think it'd be fun to build something like this! E-mail me if you'd like help.
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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Morris Dovey (in 451ea4fa$0$10296$ snipped-for-privacy@news.qwest.net) said:
| If you follow the link below, you can see what the controller would | look like. (corrected) -- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/JBot.html
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said:

Good solution, we'll toss it around in this week's meetings...you'll get the credit though!
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"Morris Dovey" wrote
Snip of some very good advice

Hey Morris,
This job is easily handled by a servo motor system. The one I'm thinking about is a stepper motor with an integral controller. This controller can be PC controlled, or you can program it to perform the very functions you describe. With four digital input/output lines, and one analog input line, you can (a) start sequence with two switches in series. This drops a shield, forces a clamp to close, start the spindle, and after a brief (programmed) delay, starts moving. When it hits the end-limit switch, it shuts off the spindle, releases the clamp (allowing the part to drop), and after another brief (programmed) delay, returns the carriage to the home position (set by the "home" switch). The analog input port can be used to set the travel speed, and you have the last output to either serve as a clamp release, or other function you may desire.
I used 3-stack 34 size motors from Intelligent Motion Systems (http://www.imshome.com/mdriveplus_overview.html ) for the assembly line battery tester; I was moving 45-60 pounds of fixtures on two axis and needed the torque. We used acme screw rod and nut to move, and used turned, ground, polished rod on linear bearings for low friction directional control.
Hope this helps ... with this approach, it's more mechanical than electrical. You will, of course, have to provide a power supply for the motor, and will need an RS-422/485 interface (available from IMS as well) to program and/or control the motor. Nice thing about the 422 comms, you can daisychain a pile of motors on one comms line (I had 14 steppers running at once in direct comms mode with no issues).
Regards,
Rick
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Rick M (in 13PTg.77157$ snipped-for-privacy@tornado.southeast.rr.com) said:
| "Morris Dovey" wrote | | Snip of some very good advice || || It would not be difficult to move your sliding jig with one or a || pair of micro-steppers and set up the jig to clamp while in motion || and release at extremes of movement. That would allow the operator || to drop the block into the jig and press a pair of buttons (one || for each hand), then reach for the next block while the cut is || being made. You should be able to feed the block past the cutter || at 3-4 in/sec (180-240 ft/min). Once the cut block has been || dropped, the jig can be retrieved at a still higher speed. You'd || need a PC (an old, recycled 386 would probably do) and a stepper || controller to drive the motors. Using steppers makes it easy to || control feed speed and acceleration/deceleration of the fixture. | | Hey Morris, | | This job is easily handled by a servo motor system. The one I'm | thinking about is a stepper motor with an integral controller. This | controller can be PC controlled, or you can program it to perform | the very functions you describe. With four digital input/output | lines, and one analog input line, you can (a) start sequence with | two switches in series. This drops a shield, forces a clamp to | close, start the spindle, and after a brief (programmed) delay, | starts moving. When it hits the end-limit switch, it shuts off the | spindle, releases the clamp (allowing the part to drop), and after | another brief (programmed) delay, returns the carriage to the home | position (set by the "home" switch). The analog input port can be | used to set the travel speed, and you have the last output to | either serve as a clamp release, or other function you may desire.
Sounds good. I think I'd leave the spindle running and only power it down if the operator failed to initiate a cycle within some timeout period - say ten or fifteen seconds.
| I used 3-stack 34 size motors from Intelligent Motion Systems | (http://www.imshome.com/mdriveplus_overview.html ) for the assembly | line battery tester; I was moving 45-60 pounds of fixtures on two | axis and needed the torque. We used acme screw rod and nut to move, | and used turned, ground, polished rod on linear bearings for low | friction directional control.
Also sounds good to me. I used essentially the same linear motion control approach with the JBot; but found a threadless lead screw and follower (DAGS: Rohlix) that I think I may like better.
| Hope this helps ... with this approach, it's more mechanical than | electrical. You will, of course, have to provide a power supply for | the motor, and will need an RS-422/485 interface (available from | IMS as well) to program and/or control the motor. Nice thing about | the 422 comms, you can daisychain a pile of motors on one comms | line (I had 14 steppers running at once in direct comms mode with | no issues).
Does help. Even nicer aspect of the 422 I/F is that it's pretty much immune to shop electrical noise over long runs.
I think perhaps you should be offering Tom a proposal. :-)
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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Tom Gardner (nospam) wrote:

In terms of force applied and energy used, two of the recommendations are appealing and can be hybridized to make a solution similar to the Roy Underhill style of work.
Saw the edges of the slot, then chisel out the waste.
Two thin-kerf blades in a dado-like setup (with washers as spacers instead of chipper blades) can define the slot edges on a table saw. Then a jointer with custom blades can hog out the waste. The benefit is: buried in a cut, the thin-kerf blades will cut true and have plenty of cooling, and only make a little sawdust. Then the jointer blades will take out big chunks of toothpick-shaped waste, taking very little energy (because the fibers are already cut at the ends).
In terms of energy required and stress on the wood, there is one better way to do the job, with a succession of passes with the right kind of plane (with knives to slit the edge and a rabbet iron to hog the waste, it can ALL be little toothpick-waste with no sawdust). Is it acceptable to set up several shapers together?
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Tom Gardner wrote:

How about a Woodmaster http://www.woodmastertools.com/s/index.cfm or similar machine with 2, possibly 3 molding heads for the slot. You'd have to use longer pieces, then cut to length because of the 8" minimal planing length. With a custom bed board you could have 2 or 3 pieces running through at once. It might even be worth a custom head from Byrd Tools http://www.byrdtool.com/shs1.html to speed blade replacement. Joe
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Tom Gardner (nospam) wrote:

Outsource this to China. Americans are unable to handle anything that requires more then 3 repeat activities
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Close! I had to farm out 90% of my woodworking to an Amish company. I just couldn't find anybody that actually would work.
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