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Thread: The "Ultimate Tabletop Machine" for Woodworkers

  1. #31
    I would like a solid bed plate that is also an index plate, with a grid of dowel and threaded holes.

    And if we're going "ne plus ultra" how about an enclosure with dust collector and Bose noise cancelling technology

    Also, if we're cutting wood and aluminum, maybe 2 spindles - 24k for wood, and slower higher torque for metal. And an additional small 60K for engraving and minute inlay work, with runout of less than a tenth for those tiny cutters

  2. What about an optional rotary axis?

    (Following this thread very closely)
    Rotary065S.jpg

  3. #33
    Join Date
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    Ok, so back on topic - my ideal router

    * 5'x10'x6" working area minimum
    * auto oiler on all axes
    * industrial controller, preferably european, and not just base model siemens.
    * laser calibrated/levelled, with report.
    * ball bar calibrated, with report.
    * 8" dust hose on pneumatic lift
    * 12KW+ spindle to run big surfacing bits/shaper bits. 2-30k rpm with a VFD that has constant linear torque curve not voltage/frequency based commutation.
    * 12 tool ATC carousel on gantry, no bed space taken up.
    * Vacuum bed with dowel holes for precision jig alignment.
    * 4th (not replacing another axis) rotary axis at end or side of bed with harmonic drive, zero backlash.
    * 25,000mm/min/1000ipm max speed, and acceleration that doesn't make that a pointless max speed.
    * 1.5-2kW servos for X/Y.. ie: see above.
    * 0.0005" real-world repeatability and cut accuracy under load. ie: drive has a step size at least 50x smaller.
    * Auto sheet feeder/clearer (I wouldn't use this, but it sure does look cool in videos!)
    * tool height setter with air jet.
    * Homes to encoded index pulse once it has hit limit switch - for perfect repeatability from home position.
    * Laser pointer in/on head for quickly aligning jigs parallel to axis. I do this with a webcam, but a laser pointer with a very fine dot (like engravers get) would do the same thing.
    * Lots of extra IO for running jigs (pneumatic clamps).
    * Wireless probing (ie: renishaw probes with bluetooth or camera+leds)
    * Air assist on head to clear slots/high aspect ratio pockets.
    * Cast iron or granite (manufactured or real) bed frame, not tube steel, for vibration damping.

    I can probably think of more, but those are the ones that really stick in my mind.



    Features on the most expensive CNC router I've used (circa $300k):
    * 18" dust hose
    * 30kW, 24krpm main spindle
    * 60krpm secondary spindle
    * 2x Circular saws that can run down x or y (loads faster than a 1/8" endmill! Maximises sheet area)
    * drilling station - not actually sure what the point of this is to be honest... I guess it has its own magazine of quick change drill bits?

  4. #34
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    not sure that fits on a table top Mark I think it also exists: http://www.cronsrud.com/extreme_series.html Joking of course.

    I would add a NEMI style grid table if money was not a concern. If I could afford that I am sure I could bank roll their wonderful pods.
    Last edited by Brad Shipton; 01-24-2018 at 9:41 AM.

  5. #35
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    In his book on design of workbenches Chris Schwarz talks about the necessity for a workbench to allow for work on the face, edge or end of boards. Having an overhang from the main clamping surface to enable working on ends of board for cutting joinery is important on my DIY CNC. Having this at adjustable angles is a definite plus, precise angles even more so. Typical "tilt box" type angle measurement is not very precise. Using a linear scale and setting a precise angle via a little trig works much better. I wouldn't need this automated, but it obviously could be.

    I don't do production work, but for those here that do, I imagine that air operated clamping options would be helpful.

    Obviously an ATC would be ideal, but for many jobs I do, having two full spindles would probably work nearly as well (in terms of how often a bit needs changing), at a lot lower cost. Even a dedicated drill head would be helpful sometimes (much more so for cabinet makers, but they probably need full 4x8 or larger machines, not the tabletop size you are discussing here).
    Colorado Woodworkers Guild
    Colorado CNC User Group

  6. #36
    Join Date
    Feb 2005
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    Canton, MI
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    515
    I'd like to see more of a modular base with locating features in the bed so you can install whatever board/plenum you want for the task at hand...vac plenum, spoil board, aluminum or phenolic for metal work, jigs etc. Can save on initial purchase price and easily upgraded/added later. Makes no sense to me that you have to pick one when you order the machine. You cloud even add drop-in locator pin sleeves to use manually for locating parts, instead of incurring the cost of pneumatic locating pins.

    I'd also like to see the dust collection designed better than an afterthought. Everyone designing the machine knows the hose will catch on whatever machinery is above the dust boot, so design the dust collection system to terminate at the highest point on the machine instead of near the bottom of the spindle.

    Create some type of total and resettable hour meter with features that tell you when to perform the various maintenance tasks (possibly in the operator interface)...is there any maintenance tasks that are not usage based? Instead of telling support 'I think I have somewhere between 1 and 5 thousand hours on the machine', tell them 2,563 hours.

  7. #37
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    Marquette, MI USA
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    Now that more like it! Even tho Mark's list is not geared towards small format machines (the topic) the features that are often available on larger ones are the ones I am looking to eke out of this conversation.
    Gary Campbell
    CNC Technology & Training

  8. #38
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    Quote Originally Posted by James Biddle View Post
    I'd like to see more of a modular base with locating features in the bed so you can install whatever board/plenum you want for the task at hand...vac plenum, spoil board, aluminum or phenolic for metal work, jigs etc.
    I really like this one...a lot. Honestly, it's something that's bouncing around in my mind relative to how I want to handle things with the machine I just ordered since different kinds of work...even when it's in wood and other non-metallic materials, often requires different setups to hold the work and do things efficiently and safely.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  9. #39
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    Jul 2014
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    Quote Originally Posted by Brad Shipton View Post
    not sure that fits on a table top Mark I think it also exists: http://www.cronsrud.com/extreme_series.html Joking of course.

    I would add a NEMI style grid table if money was not a concern. If I could afford that I am sure I could bank roll their wonderful pods.
    Pfft, you just need a bigger table! A *real* table!

  10. #40
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    Quote Originally Posted by Gary Campbell View Post
    Now that more like it! Even tho Mark's list is not geared towards small format machines (the topic) the features that are often available on larger ones are the ones I am looking to eke out of this conversation.
    Really only the table size isn't geared towards small format, and perhaps the kW of the motor - that being said, a 4.5kW motor would get maxed out by me even on a 2x2' router! The servos obviously only 600-800w would serve on a smaller machine. 4 or 6" dust hose might be better too haha.

    I've thought about building a pallet swapper (like huge half million dollar VMCs have haha) for my 2x2' cnc to try to eke more productivity out of it, if I get my funding in about 1.5 months time I'm going to add a 4.5kW ATC spindle and carousel that won't take up bed space - probably 2-3 weeks of engineering and building and a couple of thousand USD (finally found a cheap BT30/ISO30 ATC spindle!) If the government is nice though, that might turn into the 5x10 ATC router I was planning to buy later in the year though.

    Once I get back to production I'll be getting 10x ultra narrow/low profile pneumatic clamps machined up for my #1 product's jig, it's going to save me about 1 min per cycle in manual effort, that will need 10x IO on the controller and save me about 400 minutes on the first batch (a whole day) I make. It's only a day every 2 months, but it's also removing one of my most annoying manual steps. The new jig design around it will also save me probably an extra 4hrs of machining new jigs every batch (because I destroy the current ones due to the design haha).

    Homing to index pulse is actually pretty awesome, and not something most cheap PC based controllers can do - although I wouldn't be surprised if linuxcnc could, i really need to take another look at that, it's been 10 years and i'm sure it's improved a lot! With my inductive prox switches and Mach 3, I home to about 0.2mm of the previous homing. Doesn't sound like much, but if you "save fixture" every day when you shut the machine down before finishing up, this can be cumulative (if the first homing when you set the jig up was -0.2mm relative to each subsequent day, you'll get 0.2mm of creep per day, 1mm per week) With homing to the encoders index pulse after homing to the machine's limit, it should be within 1 encoder pulse (1/10,000th of a rotation in my case) so each subsequent day it's perfect. On small stuff, 0.2mm of offset on say a chamfer is pretty visible as an offset from centre to the naked eye.

    Since I didn't mail my bed (already spent $1k on shipping...) here, I'm looking at redoing my bed with a laser cut steel plate with dowel holes for jig alignment, as well as some threaded holes for clamping metal down. Then I can put the whole router in a "tub" for using flood coolant if I want to make a mess of my shop and cut metal again ahha.

    I wish I had a tool height setter (not a touch off for the top of the work!) every time i change endmills... i'm going to change that... it's been on my todo list for 3 years! It's coming up pretty soon, i'm sure it is!

    Probing.. wireless or wired for a tabletop machine is pretty priceless, I'd just that pretty much every day. I put a lot of planed to size wood into the router and need to make pockets or drills into it in precise positions relative to the edges. Same goes for double sided machining - touching off the otherside rather than relying on it's position in the jig.

    Vacuum bed as I've said before isnt useful to me, as I don't do sheet goods (other than jigs) but for most people using cnc routers, sure. I use my router more as a mill for wood... so am more into metalwork mill style workholding haha.

    That list is pretty much based on my wants in a machine of any size... they might seem overkill for a small format router, but i'd use the heck out of everything on the list if it was on my router - and you did want cream of the crop features!

  11. #41
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    Elizabeth, CO
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    A question for you Gary:

    I know servos have encoders and close their PID loop that way. Is it possible to instead set up the servo feedback to come from a linear encoder so it is based on the actual position of the axis and not the rotary position of the servo? I think this would provide the best overall accuracy. This would require the cnc controller (not each servo controller) be involved in the closed loop positioning.

  12. #42
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    Richard...
    Possible, most likely yes, probable or practical, most likely no. First you would need accurate absolute linear encoders, capable of high speed operation, 1 near each motor. You will also need a very expensive control software that can interpret those encoders in real time and balance the differences between a dual drive axis. And then you may need $50k plus in equipment to calibrate it all.

    What contract have you signed with NASA that needs this king of accuracy? In all honesty, if that was the best way to achieve a high level of accuracy $300K & up machines would be using it. I don't think they do.

    In actuality only LinuxCNC and a programmer might be able to do this with a PC based control. You would most likely have to use Centroid or your pick from what I call "the F's and G's" of proprietary industrial controllers.

    With most servos capable of sub .001 accuracy why would you need to reinvent the wheel?
    Gary Campbell
    CNC Technology & Training

  13. #43
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    Quote Originally Posted by Gary Campbell View Post
    With most servos capable of sub .001 accuracy why would you need to reinvent the wheel?
    I only asked because this is the “ultimate” thread, and several here seem to want to mill aluminum. Direct position feedback would be the “ultimate”.

    I actually have designed for NASA and currently have lots of my designs flying on the International Space Station. None of them had any tolerances of .001 (tightest I recall was +/- .002 ) and some are made of some fairly exotic materials such as nickel cobalt superalloys. I have worked on parts for other customers that required cylindrical profile tolerances of .000010, so I am familiar with the challenges in making and measuring high precision work (electro optics).

    I am personally quite happy with my DIY open loop Nema 23 steppers, Gecko 540 driver, supported round rail, 8020 framed, rack and pinion drive machine. I built it as a hobby machine for cutting wood, and spent less than $2700 (including a dedicated computer and software) and I have a 50x60x6 inch cut area. For me, it is better than any commercial or kit machine I have seen under $6k, and many that cost much more (have several friends with Legacy machines - I like mine better).
    CNC Overview.jpg
    I also greatly admire the machines of yours I have seen and recognize that they (and even others such as the Camaster machines) are in a whole other class than mine. If I had the money to spend, I would build or buy a machine closer to those discussed in this thread. I may upgrade mine in the future, but have not yet run into any issues doing what I want to do. The only problems I have had is trying to machine aluminum without coolant, some day I may build a smaller machine that accommodates coolant.
    Last edited by Richard Gonzalez; 01-26-2018 at 2:53 AM.
    Colorado Woodworkers Guild
    Colorado CNC User Group

  14. #44
    Join Date
    Mar 2014
    Location
    Iowa USA
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    Nice job Richard. I guess since I do not have $10k to spend on a tabletop CNC machine unless its making money for me I will need to use what I have. But I do have a lot of other "toys" (besides what listed below) and if as my loving wife said sold them off, I could afford a more expensive machine! No thanks.
    Last edited by Bill George; 01-26-2018 at 8:58 AM.
    Retired Guy- Central Iowa. , LightObject 40w CO2 Laser and Chiller, MakerGear M2 3D Printer. Fine Line Automation 4x4 CNC Router- Mach4 ESS

  15. #45
    Join Date
    Oct 2009
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    Richard...
    Nice machine, you should be proud. It looks similar to one I built, my first home build a few years back. https://youtu.be/rKGc9DnKix4
    It was a microstepping "mythbusters" machine that actually had enough mechanical reduction to allow from full to 1/10 microstepping. 1/10 microstepping has really smart people on both sides of the debate and I wanted to find out what worked the best, at least for me. I learned I will never use 1/10 microstepping on anything with a changing load (CNC router) again. It returned by far the worst results on the same vectors on the same machine in the same material block.

    The attached pic of a drill mount was cut all full steps, using a 1/4" oflute (3/4 DOC) (60 ips, 15k rpm, .085 per pass) in 1" material as you can see by the shank rubs. Also removes doubt as to Oflute bits being ground undersize. It was cut using only a stream of air for cooling.
    Attached Images Attached Images
    Gary Campbell
    CNC Technology & Training

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