Does anyone know which Eccentric is better... 1/4" or 6mm?

 

A small note on the parts list would be helpful, as I've seen this asked many times and I know I questioned it myself when ordering parts.

 

As long as it matches the spacers, one should be ok. The more important aspect would be the 'shoulder' of the eccentrics, right ? More recent OBPS is 10 mm outside diameter as opposed to the older 8 mm.

The 1/4" are a hair longer (0.35 mm) so it could affect screw length (ex: X axis has a few spacers so it will add up) but could also give a bit more clearance. Not certain how much it will affect alignment of the wheels though. One would need to take measurements to 2x check. What is the tolerance on these things anyways, including the wheels ? I'll have to double check the OXcalculator for this aspect as I forget what I did (time for an update of the thing as well).

Have fun ... I'll be spending the afternoon with myOX, the wife will be doing 'girl time' with the daughter.

 

Tell me about it. I (accidentally ?) ordered regular head screws (twice the thickness ?!) so I had to sneak an extra shim (or was it 2 at some spots ?) to clear those big heads. But it worked just as well ... as long as the respective screws are also long enough - extra mms added by the extra shims.

 

I would just like to say thank you to Mark.

My open build parts arrived this morning to my home in Canada.

Parts quality is excellent and the packaging was a work of art... Today was a very special unwrapping day...

 

Nope it was just good ol 10w30 Valvoline for my sisters car. I guess I didn't know a lubricant can be 'too' good. First time I've heard that, and I've read many things Have a good source on that? Would be good information for the newer people that are starting to cut.

Must have been someone else you helped with the drag knife, I sent brian money for beer and set the cam for it pretty easily. His cad drawing doesn't leave anything to the imagination. Yes, it is the Grunbalu knife
Didn't work too well for me, but I need to try it out again after adhering my 'work piece' down better.

 

I remember being ticked I had to spend an hour unwrapping everything

 

Thanks for putting together this great site with tons of info. I am new to cnc and noticed most setups are: computer>controller>motor driver>motor, But with your ox setup, at least in the videos you don't include a motor driver but yet the system still works, why is that? Is there a driver built into your controller? I was looking at doing (3) NEMA 23 motors and a planetcnc mk3/4 board. Thanks for the input.

 

Some controllers, like the CNC xPro, have integral drivers. Others, as with Arduino with a driver shield, have smaller drivers "piggy back". The ones you have seen have separate drivers, usually to drive more current (amps), allow separate power supply for each of the stepper motors, ... Call the latter more 'professional' or 'higher end'. The former are still very good, more affordable,... and they work for lots of people. Controllers like the CNC xPro are real easy to use - I took it out of the box and plugged everything in, it ran.

You might want to use four steppers, 1 for Z, 1 for X and 2 for Y, especially if your X is wide. Unless, of course, you mount the Y in a central position (below the work surface) like some have done (usually still narrow machines).

 

Homing problems...

I have completed the OX, and built a box to house controls, and ran cables through drag chain, etc. Looks great.
I also hooked up homing switches, and this is where my problems have begun. The homing switches are set at the "near" front of the machine, so they would be triggered at the front left of the machine, with z-axis at max height. When I run through a homing cycle, the machine homes properly (i.e. gets to the correct location at front left of machine), but then the workspace is all negative space. Grbl now thinks that the 0/0/0 location is at the upper right hand corner.

The steppers are set to move away from lower left for positive motion, and I inverted the homing direction settings to indicate the limit switch positioning.

I can't reset the machine coordinates to 0 at the lower left, just the work coordinates.

Without homing, I can move the spindle to the front left, reset to zero, and everything works as expected.
With homing, grbl thinks 0/0/0 is now at the upper right.

Running grbl 0.9g on XPRO CNC controller.

Any advice would be appreciated!

 

Okay, I figured some things out! Basically, it doesn't matter what the machine position states - in my case it is set at the max soft limits of the workspace. Resetting to zero resets the work position as expected. So basically just user error on my part.

One final quirk - using UGCS when I hit return to zero it goes to work coordinate zero and then continues to move to machine position zero (at the opposite end of the table). If I just execute G0 X0 Y0 Z0 it goes to work coordinate zero.

I'll post some pics soon!

-- John

 

If I remember correctly the 6mm eccentric was added to the part store because it worked better with the metric spacers and the metric dimensions of the v-slot.
-Nugz

 

This is my first post and I apologize in advance if this is the wrong forum to post the following questions.

I'm new to CNC and have a growing itch to build/assemble one. My goal would be to have a machine to do some small scale production of some woodworking products but also be able to mill some limited amount of aluminum as well. My preferred size of cutting area would be 2'x4'.

I can't afford to spend $3-4K on a higher end kit, let alone a fully assembled commercial unit. I'v been looking at various kits and really like the OX. However, what's not apparent to me if the OX is suitable for production work, even on a small scale. I like the quality of construction, but are the V-Slot rails with Xtreme wheels and belt and pulley drives appropriate for this type of application, even with aluminum gantry plates?

If not, are there modifications that could be incorporated to make the OX a more robust unit suitable for my needs such as a different drive system, restructured gantry, etc.? Or, do I need to look down a different path?

Any feedback or suggestions would be greatly appreciated.

Thanks,
Shawn

 

people do do production work on ox's on a hobby level.
what type of production are you looking at 5 units a day or 500?
Bob

 

Bob,

I envision making about 25-50 items a day. It would be setup to mill an array of 24 items on the table at one time. My objective would be to have a small side business selling wood crafts to make some extra money and using the the CNC router to leverage my time.

Out of curiosity, what dictates the production capabilities of a particular CNC router?

Shawn

 

Shawn
I don't really know where the line crosses from hobby to production.
With the ox your spindle will be one limiting factor, a trim router isn't meant to run for hours at a time.
Another difference between a 1000.00 ox and a 3000.00 cnc is most likely also speed, on the ox your speed of cut (depends on what you are cutting) you might be looking at around 40" per minute, the 3000.00 cnc might reach speeds closer to 100" per minute or more.
But what you are saying 25-50 items a day loaded 24 at a time on the table I'm sure the ox is quite capable of doing without much problem...
Bob

 

I'd say the speed you can mill parts is ultimately dictated by feedrate's. And feedrates are dictated by spindle size, machine rigidity, actuation type (belt, rack and pinion or lead screw, each have different torque ratings) And stepper motor torque. other defining factors are the material and milling cutter your using and coolant if any.

Setup and Handling time and tool changes, would also need consideration. Along with finish quality.

I have had single 2.5d small part take upwards of 4 hours, and 25 2d parts in under an hour. So really it comes down to the part.

To better anser your question as to wether you may be able to achieve the rate of production your looking for, you would probably need to post or describe the parts you would be milling.

Hope this helps

 

Bob,

Thank you for the great feedback. It is very much appreciated. I agree with your comment about the trim router, and I should have previously. Could the OX support a full size router with some structural reinforcements?

Also, I spoke with someone who's operating a ShopBot Buddy machine and he made the statement about loading the machine and letting do it's thing overnight. Is this a sound approach in utilizing a CNC router? Assuming I've worked out the details, can I let a machine run during an unsupervised, graveyard shift?

Thanks again,
Shawn

 

Personally i would never suggest running a machine unsupervised for any long period of time. All it takes is some material getting clogged in a deepish pocket and a dulling bit to start a smolder which can be ampified by exhaust or suction to stoke a flame.

I have no doubt people do such a thing everyday though.

 

Just do a search in the Shopbot forums, a few guys have had their machine and garage go up in smoke due to a vacuum burning out, or a bit smoldering MDF... First rule of thumb with a CNC, NEVER leave it unattended for more than a few minutes, or do so at your own peril. I run mine pretty much 7 days a week cutting signs, I can't count the number of times something bad could have happened if I wasn't in attendance. Just my 3 cents..

On a lighter note, like Jonny Norris said:

It really depends on what materials you plan to work with, router/spindle choice, machine structure, and how fast you can cut. I don't completely agree with Snokid on the router versus spindle issue. I have used the same router on my large machine for 2 years now, just changing out the bearings and brushes when necessary, some days it runs 14 hours pretty much non stop. I can't say the 1 1/4 compact DWP611 i'm using on the small machine will take that kind of use as I haven't put it to the test yet, but I will be. Not any different than my 3 1/4 Porter Cable just smaller.. If your just cutting out 2D or even 2.5D parts I wouldn't worry about the added cost of a spindle. I could buy 4 or 5 Dewalts for the cost of a decent spindle and VFD. My Clydesdale build addresses alot of this and some ways to make a stronger small business oriented machine.

http://www.openbuilds.com/builds/clydesdale-cnc.1428/

You can check my original build to see some of the issues I was having pressing the stock Ox into a small production environment.

http://www.openbuilds.com/builds/florida-ox-2x4-with-vac-table.1270/

Good luck and hope this helps !

 

Point taken...not a good idea!

 

Jonny,

To answer your question, I'm exploring the idea of making cribbage boards out of a variety of materials including hardwood and aluminum. Besides drilling the obviously countless pegging holes, I would be milling larger pockets for holding cards as well. Additionally, I would like to incorporate some inlay work and some engraving. What I was considering is creating a slide in table/spoil board with cutouts in it to hold an array of boards to be milled at the same time. Then I would also like to be able to take the slide in spoil board which hold the cribbage boards and slide it in vertically off the end of the table to mill the ends on some of the cribbage boards.

Hope this answers your questions...

Shawn

 

myOX is using a full size (MasterCraft) 12A router with pretty much the standard OX configuration and a 1500mm (or so) X axis. I have not checked for deflection of the double 20x60 X beam, but it looks good for what I am planning to do so far... The NEMA 17 is having a bit of problem keeping the router up during idling, especially on long jobs. I will need to either up idling time (255, always powered, being an option) and/or change to a NEMA 23 (stronger "hold")

It has a high duty cycle, but not certain how it would do after hours of none stop routing. I might need to sneak a few cool downs in long jobs ... Routers are not meant to run non-stop, even for just a few hours. I believe that would be the advantage of using a (true) spindle over a router. Although the Mastercraft router I went for seems to have a strong fan for cooling (it sure raises dust cloud when working on MDF !)

As for running unattended, you will definitely need good (no false trigger) limit switches so the router is not rammed beyond the limits of your machine (accidents do happen when least expected) nor stopping because of excess chips or dust getting in way.

If the bit breaks during the unsupervised jobs, your machine will keep on cutting (air, since bit is now shorter) with wear on your machine (steppers, router, controller, ...) possibly for several hours since you are not around to stop things.

You don't want a bit to spin jammed in a part for too long as it could start a (friction) fire ... say a GT2/GT3 breaks mid run.

If working aluminum and using a coolant spray, make sure the coolant tank is full and sufficient for the run.

It would not hurt to have 'shields' to avoid any parts coming loose and flying off and jamming things, even if supervised for that matter.

I would at least have a webcam to keep eyes on things every so often. My portable has a webcam ... I could just remote it. Or just find something else to do in the garage (or room) while your machine is nibbling at some hefty chunks of wood or whatnot ... frequent quick peeks, the ears listening for any strange sounds (never wear headsets blasting music while working !)

Don't forget to check on your vacuum's canister capacity ... don't want it to overflow either during one of those extra long runs. A real shop dust collector would do the trick oops: I should of kept my dad's after all !)

My worry on long jobs is a power failure, especially minutes before finishing the job! The generator (half the house is on it) has a minute or so delay to avoid starting for short brownouts. But that's plenty long to royally mess things up. The computer will stay powered (a portable, so plenty of battery time built-in). The controller will stay powered (USB port). The steppers and the router (spindle) could be too much for the average UPS and they won't like the switch over time, even if just ms ... Definitely would need an inline UPS with no power sags (at high loads). Don't forget, it takes longer to recharge a UPS then to discharge one. So, if like me, you are in an area prone to brownouts and power failures (I'm in a region with, based on a 10-year average, 35.9 days/year of lightning strikes - record, nearby, is 47!!), get one with plenty of battery time as brownouts/power failures are like earthquakes, a few more will follow as hydro services are being worked on !

If you don't have appropriate power backup, what happens when the regular power returns, even after a short brownout ? You'll loose more than just a step or two in all axis and you don't want your machine to just continue unaware of its 'blackout' period.

You may want to segment runs into shorter 'jobs' and check on things between segments as you will have no choice but walk over to start the next segment.

Just thoughts as I'm trying to figure the same things out for myself ... standing looking at myOX work for 45 minutes is 'fun' for a few first jobs. "Wow ... its a machine I built doing that!" I'm certain it won't be as fun after a few dozen jobs, especially those real long ones being planned for the next few weeks.

 

Serge E.

Interesting points about leaving a machine unattended. I never considered the potential electrical problems. As you and others have pointed out, it appears the risks far outweigh the benefits.

 

Hytech2K, your Clydesdale build is very helpful. Great looking machine and a very detailed build. Looks like rack and pinion is the way to go. Are you satisfied with rigidity of the 4080 gantry beam? Do you think you'd be able to install a full-size router on the gantry? Is there anything else you'd change or recommend? Do you think you would be able to mill 1/2" aluminum your Clydesdale machine? Thanks again...nice work!

 

Thanks! I'll be finishing the rack and pinion tonight and post some videos of the whole thing in motion. The single Misumi 4080 beam is much much more rigid than the twin 2060 extrusions. When you say full size I assume you mean like a 2-2 1/2 hp router and yes I would, BUT the problem just isn't the beam strength, you will most likely run into issues with your Z slide setup. Here's the thing based on what you said you would like to cut, you can make some upgrades and cut softwoods, phenolic board, acrylic, and hardwoods slowly. Aluminum be much harder, you will either have to cut ridiculously slow or you won't be able to at all. Cutting aluminum with a router spinning way faster than mill speeds requires a fast feed rate to keep the aluminum from sticking to the bit and breaking it. Toolstoday's recommended speed for their "O" flute 1/8 bit is 30ipm and 120ipm on the 1/4. That's not going to happen on a regular Ox. Should be able to cut 1/2" aluminum on the Clydesdale, if the DOC if kept pretty low, there's not much difference between being able to cut 1/4 to 1" feeds and speeds for one work for the other, once it's all back together then i'll start testing it. I don't really plan on using it for that, I have another machine I use for aluminum and brass.

As for anything I would recommend, read every build you can on here that pertains generally to what you want to do. Cutting aluminum without a ton of chatter and to be able to feed properly takes a rigid machine.

 

Okay, so they would require milling on both faces. You mention a spoil board with cut outs to hold the pieces, in regards to producing 25 a day, your going to have to reduce any handling time to a minimum.. personally i would, if possible mill all the parts from a single sheet, using locating pegs in each corner so you can simply flip the sheet to mill the other side.and use tags/tabs to hold the parts during the final contour cut. but at a push you could indeed mill 25 wooden parts in a day, however i very much doubt you would be able to achieve 25 aluminium cribbage boards in a day at the quality you would require.

Large format ox builds do unfortunately suffer with flex which makes milling harder materials like aluminium slower than you would be able to in a smaller ox.. and really to mill aluminium you would need a coolant.
I would suggest, by the sounds of it you require 2 machines, a smaller ox, say 500 x 300, with liquid cooling to mill individual aluminum boards. Though converting a vertical milling machine to cnc, would be your best option.

Jon

 

Anyone here used encoders? I was wondering if encoders could be used to switch off the machine in the event of an anomaly.