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Messages - Tool-n-Around

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46
CamBam plus feedback / Re: Hey Andy, What can we do?
« on: October 08, 2023, 16:21:53 pm »
Not sure I can add any more to what has already been said but just felt I'd add my 2 cents anyway for what it's worth. I'm nowhere near as invested in CB as many of the site regulars here, but have several years and many CB programs that I use. To me, the cost of the software is a pittance compared to invested time learning and using the software.

I selected CB because it was recommended to me by a member of this forum and have since received invaluable help from the members of this forum. I have promoted it to many as being an excellent value, and many of them started by lurking here and of late, sadly have concluded it is unsupported software and would be a risk.

People's interest change over time and if Andy has moved on, that's understandable, but it seems to me that given the considerable effort CB's development must have been, and the interest's of the customer base, why let it fade into obscurity from lack of attention? Why not sell it or pass it on to someone that could continue to develop it and support the owner/user community?

Best,
Kelly

47
Members Machines / Re: Contemplating some upgrades to my CNC Router
« on: August 31, 2023, 19:19:09 pm »
Got my Y and Bed beams ground and rail lands machined on the Gantry Beam. The steel bed beams are just 2x4x1/4 & Y Rails 2x8x 1/4. My bud's shop has all kinds of surface grinding equipment. These are by far the straightest things in my shop and could be my primary standard straight edges. I have ground 1/2" MIC 6 plate for the bed surface. I also have 2x4 stock for the legs and plenty of steel for a sturdy base. Guess I'll have to get on with ordering steppers, controller, and building it out. I have a zillion mounting holes to drill and tap for the linear rails.

Best,
Kelly

48
CamBam help (General usage) / Re: DXF Exports from CB
« on: August 12, 2023, 13:52:01 pm »
Appreciate the explanation - and the fact that the cost of CB (compared to AutoCAD) is a major benefit but having used CorelDRAW! since v0.9 and never used what many would concider a 'real' CAD program, I found CB very limiting. If it's all that you have, then of course it is useful but the OP obviously has 'real' CAD software and it's understanding why he's using CB as the origination that I'm having difficulty with.  ???

Well, I am the OP so I think I understand my motivations :)

I bought a CNC router a few years ago and had no CAD or CAM software or experience at the time. After messing around with free trials of several softwares I bought CB. Most of my machining could be done with relatively simple 2D and 2.5D machining and modeling and both were easily done within CB. As my projects became more sophisticated and involved 3D machining, I did find CB limiting so I did by another CAD program. But, I don't find 2D modeling in CB any more difficult than other CAD software. Besides not having to jump between softwares, havng all the geometry native in CB can be helpful when especially when you need to generate additional geometry like tool path boundaries, etc, but I will say I value CB's CAD features more highly than most all forum members.

As far as my CAD goes, I'm primarily just generating surfaces for 3D machining in CB. If it's a one and done project, then the importance of parametric modeling is lessened but if I wish to make variants of the part changing size/shape/location of similar features, then it does matter, and thus far, how DXF imports/exports are interpretted and may affect the solids and surfaces creates as many problems as it solves for me so I'm better off just sketching geometry in the native CAD software unless it's very complex. Maybe that'll change wih a better understanding of how the various programs generate and interpret exports and imports, which obviously from the posts in this thread is not constant. -Thus the thread.

Best,
Kelly

49
CamBam help (General usage) / Re: DXF Exports from CB
« on: August 12, 2023, 02:34:10 am »
I'm somewhat mystified as to why this thread is still running and - more to the point - why I cannot fathom the point of EXPORTING a DXF file from CamBam. The way I work is that CamBam is the last port-of-call for any design I need to create. By the time it gets into CamBam the only thing left to do is create the G-Code ready to manufacture. I can't see what I must be missing.   ???

What you are missing is CB has CAD capabilities that for someone that is only doing 2D, 2.5D, or simple 3D machining are quite adequate. Getting that CAD/CAM capability for the price of CB is a good value IMO. In fact I frequently use CB to make simple surfaces for 3D machining but when I develop and further refine designs, I often need to use a CAD program to model more complex parts but I frequently have relevant geometry available in CB......so why not use it?

Best,
Kelly

50
CamBam help (General usage) / Re: DXF Exports from CB
« on: August 11, 2023, 14:34:16 pm »
For what it's worth, here is the resulting part made from the subject geometry. It's a drop base automotive air filter. The lid has turning vanes that reside above the carburetor boosters. Both the base and lid have 3D surface machining. The shapes were ideal for waterline finish but I have become so frustrated with WL finish, I will only use it as a last resort. I have reviewed the documentation and David's 3D tutorial multiple times, but still experience inordinately long times to generate tool paths and gcode, and frequently have cutting errors. In preference I almost always use scanline MOPs with very fine step over (and resolution if needed). SL just works. WL Finish, not so much. Maybe I'll revisit this with a dedicated thread when the forum becomes a little more stable.

Best,
Kelly

51
CamBam help (General usage) / Re: DXF Exports from CB
« on: August 11, 2023, 14:13:08 pm »
.......I downloaded the file and it and it only consists of polylines, this is down to the exporter used (and it’s settings)......I then exported the file as dxf from CB and there are arcs and lines in it. This is down to the way your 3d cam program is exporting the file, even though the dxf files are both AC1009 they have different headers and content.

The DXF file I posted with straight segements was created as a CB export. It displayed that way in Alibre. I did take in quite a few of those DXF export threads on the Alibre forum but the original file could not be made to display correctly (at least by me) by manipulating Alibre settings. When I changed arc fit setting in CB and re-exported, as suggested by Eddy, that solved it so I moved on......but (more below)...

I need to look at the posts and attachments David posted. With the forum crashes, I hadn't reviewed those replies, but the thumbnail has me scratching my head a bit because my original file only had nodes between the arcs and straight segments, no extras.

I actually ended up having to re-sketch the 2D CB geometry in Alibre, use it to creat a solid, then surface, then back to CB for CAM. The soilds were lofts from the sketches and the lofting did strange things because of (I presume) the nature/cunstruction of the segments in the DXF line files. I still have a long way to go with my Alibre skills. I find CB to be much easier for creating 2D geometry than sketching in Alibre. But then there is getting the sketches fully constrained for further modeling use....and in order to do that and make parametric models I'm just better off doing it all in Alibre.

Have you had the machining on the Y Axis rails yet.

I've been making a lot of other automotive castings but have projects in the works that will need the expanded envelop of my new machine. I just got the Y-beams and am sourcing the bed beams and legs now. When I get those, I'll have the bed beams and Y-rails ground. The Ys took some time to find because I didnt want to buy a whole stick for the two short remnants.

Best,
Kelly

52
CamBam help (General usage) / Re: DXF Exports from CB
« on: August 10, 2023, 13:10:15 pm »
....I think Kelly’s issues are to do with the importer\exporter settings in his cad software as I don’t have don’t have to explode or arc fit the geometry.

Thanks Dave, I'll play around with my CAD settings but one other thing I thought was interesting was the thumbnail of the CB DXF Export file attachment in my post above also displays on this forum as it does in my CAD import.....straight segments.

Best,
Kelly

53
CamBam help (General usage) / Re: DXF Exports from CB
« on: July 30, 2023, 19:20:38 pm »
1. Select the polyline
2. Menu item, Edit->Polyline->Arc Fit
3. use a Tolerance of 0.01

Thanks Eddy, that did it. I had (mistakenly) thought that arcs in CB were automatically created at the default selection for arc fit.....apparently not. Also I wasn't entirely clear on the meaning of arc fit as stated as "the maximun allowed error between arc segment and midpoint of source segment". Polylines are actually a lot of small straight segments, correct? So would .01 Arc fit mean that each arc segment was .01 mm long or .01 inches long depending upon units used when twas he cb file exported for use?

When I import the same dxf file without the arc fit applied back into CB, why was/does CB able to interpret and display the arcs as curves whereas my CAD program as straight segments? When I double clicked the DXF reimported to CB, I expected to see a see of red squares on the arcs but instead there was just one at the arc mid point as originally displayed before arc it applied. -Just trying to learn something here.

Best,
Kelly

54
CamBam help (General usage) / DXF Exports from CB
« on: July 30, 2023, 17:24:54 pm »
I'm having a problem using DXF exports from CB. I probably don't have my settings correct in one or both programs but when I export a Polyline to DXF, the arc segments appear as straight lines when I import that DXF file to CAD, in my case Alibre Design Pro. If I reopen the same DXF Export in CB, it displays at it originally appeared as the polyline from which the DXF was created. I'm guessing it's something like the arc fit/number of arc segments selected since each arc in the polyline has only two segments/nodes which are displayed as straight lines in my CAD program, but I can't find where to adjust that setting in CB for that polyline. Any pointers?

Attached is the original CB File, the DXF file as exported from CB, and screen shot of how it displays when imported to Alibre.

Best,
Kelly

55
It's a little hard to tell from your description but here are two interpretations of the geometry you describe and two methods to cut the three dimensional profile.

Each surface was generated by drawing a profile, using revolve extrude to generate each surface, then rotating the surface normal to the XY plane.
A 2D pizza pocket was drawn to use as the machining pocket and bounding region.
In the first example the 2D bounding region was used with the surface 1 and Scanline 3D machine Operations (MOPS)
The second example is a little more complex, but first, the 2D pocket is used to generate tool paths. Then the Toolpath to geometry command is used to create polylines from those tool paths. Then those tool paths are projected onto the surface. The engave MOP can then be used with those projected tool paths to cut the 3D surface.

Sorry, I had to delete the tool paths for the second method because it made the CB file too large to post, but I did include a picture with the tool paths of each outcome.

I'm sure one of the guys here can do a better job of decsribing/explaining the two methods than me. I'm just a hack that's knows enough to get by.

Best,
Kelly

56
Members Machines / Re: Contemplating some upgrades to my CNC Router
« on: June 15, 2023, 02:39:15 am »
Nice video’s Kelly, I was wondering how you were getting on a few day’s ago as you keep up a frenetic pace and hadn't posted for a while.

Thanks Dave. I've been using CB quite a bit but when I run into a problem I just figure it out or work around it as opposed to bothering the forum folks. When I build the control system for the new machine, I suspect you could see some questions.

Best,
Kelly

57
Members Machines / Re: Contemplating some upgrades to my CNC Router
« on: June 14, 2023, 18:43:32 pm »
Still plinking away. I drilled, tapped, and countersinked, 120 5mm fasteners. Used small shims bewteen the casting and skin at each fastener to set the glue gap to .005" which according to the Loctite specs is optimal and yields 3500 psi shear strength. I need to call in a favor from a friend to machine the registration lands for the linear rails because my old knee mill has neither the capacity nor accuracy. Long way to go for a beam. Hope it peforms well. On to the Gantry plates.

Best,
Kelly

58
Members Machines / Re: Contemplating some upgrades to my CNC Router
« on: May 26, 2023, 14:50:43 pm »
I don't spend as much time in the shop during the fair weather seasons but still plugging away. Here's the gantry beam. It's an assembly of the two lost foam castings end to end, and then the two faces get skinned with 1/4" aluminum tooling plate. Each casting half weighs 14lbs and together measure 44"x 8"x 4". Everything gets screwed and glued together with structural adhesive.

I didn't want to make them in halves but it's sort of with my capabilities as far as casting and rough machning for assembly. Even so, the two finish machining operations on the ends and prepping the surface for the rails will need to be done at my buddies shop because I dont have the travel nor accuracy to machine the surface for the linear rails. I figure it will weigh 40% and be at least as stiff as a 8"x4"x1/4"w rectangular steel beam. The gantry plates will also be castings but the rest of the structural rectangular steel.

https://youtu.be/DOpBRa-_xT0
https://youtu.be/j4okXkw72eM

Best,
Kelly

59
Members Machines / Re: Contemplating some upgrades to my CNC Router
« on: April 04, 2023, 15:28:57 pm »
…..I was watching this video the other day, How NOT to Design a 5 Axis CNC - YouTube

Funny, I just watched hat (Mach Super’s) series last night.

A lot of engineers posted in the comments saying that his observations were correct.

I did take note of those comments. I may increase the fabricated aluminum X-Beam from 8x3 to 8x4 just for a little more torsional rigidity. Problem is, the spacing on the linear bearings on the gantry plate eats up a lot of Y-axis travel, in my case, 12”. With other packaging, it means I have just over 625mm usable of my available 1000mm linear rail . Even with my previous efforts to minimize the distance to Z/spindle centerline, along with the thickness of the X-Beam, I still can’t get my spindle axis centered between those two bearings on the gantry plates, but I have 25mm rails and bearings on the Y so I think I’ll be just fine as far as bearing loading.

…….A servo drive has its rated torque up to its rated speed and doesn’t drop off like a stepper. So for example if you replace the X axis stepper with a 3000 rpm servo, and gear it down with the pulleys to your required 500 rpm then you get a 6x increase in torque and resolution meaning that you can select a relatively small and therefor cheaper\lighter servomotor. The only downside of a servo is the price.

Stepping down 6x….hmmm. I had not considered that. I suppose that would also mean any small error introduced by the belt and timing gears would be 6x smaller too. Those long stack NEMA 34s are big and weigh 5.5kg. Taking a quick look at the Steppers Online offering, their E-series only weighs 2.5kg and is quite compact. With driver they are $230/axis with driver plus $150 worth of timing belt and pulleys. With 6:1 reduction it would be $380/axis…..or $1520. More for their higher end T series.

The E-series 1000w servo is 3Nm and $260/axis, which is about the same torque as the closed loop N34 stepper ($160/axis) at 500rpm with no reduction, but the stepper torque triples at the lower speed range which in my case is the majority of use.
Being the machines intended use and being a hobby machine, I sort of doubt that I could really fully appreciate the benefits of servo vs N34 driven system, especially if I can direct drive the steppers. The way I have it laid out, the hardware could fairly easily be retrofitted with either a step up or down timing pulley system if I got into a jam.

The hobby servos that you would be interested in have step and direction inputs, meaning that they are a drop in replacement for steppers, be careful of the industrial servo’s as they might not have that interface as it’s to slow, for example with a Clearpath servo you connect up the power and step\dir inputs to your existing controller and off you go.

I’m not quite at the point of pulling the trigger yet but for my relative level of cnc sophistication and use, it’s probably silly to do more CL N34s. Either way it’ll be a huge step up for me.

…With the gantry endplates, there are a lot of videos on utube were the Y axis rails are mounted higher up off the bed to keep the endplates short and stiff, this also drastically cuts the moving mass of the gantry.

I sort of split the baby on that. My bed surface is halfway down the height of the 8” tall steel Y Beams so with the bottom of traveling beam in lowest position, the traveling X beam is at the very bottom of the gantry plate. It will probably be rare that it sees duty in the more prone/higher positions.

Thanks for all the input Dave. Much appreciated.

Best,
Kelly

60
Members Machines / Re: Contemplating some upgrades to my CNC Router
« on: April 03, 2023, 13:41:44 pm »
Not much traffic on the forum these days so I’ll throw this out there.

I have been refining and finalizing my machine design. Without reiterating all the details, I’ve decided to build from scratch and sell my existing machine. For my use, the new machine is a tradeoff between big envelop/high(er) speed yet still retaining decent rigidity for occasional hard plastics and aluminum plate cutting. It’s turned out to be quite a pair of opposing goals. I’ve settled on a moving gantry approach, just for the work envelop, and make the best trades in (low) mass of the moving gantry and rigidity. To aid in the latter, the traveling (my X)  beam is repositionable, 12.5” and 5.5” max/min height under gantry respectively. I expect it to spend most of its life closer to the lower position shown and moved upward for big(ger) envelop light foam cutting. Max usable cutting envelop 30”x 24” x 10.5” with 2” CL bit. I did increase the dimensions of stationary steel beams to 8”x 3”x 1/4” (from 8x2) and the fabricated aluminum traveling beam to same dimension. I figure all in with all components and hardware, the traveling gantry with Z axis and router will weigh about 160lbs.

I’ve been revisiting my thinking on motors and drives. Just checking myself here but:

As a recap, my top (foam) machining speed is 200in/min (5080mm/min). I have designed for 10mm lead ball screws so the ball screw rpm would be 508 rpm direct drive. I’ve got a 3:1 timing belt mechanism designed in between the stepper and ball screw as shown in the attached, with the intent of keeping the stepper in a more optimal torque range.

Looking at the attached torque curve, it doesn’t look like I’m really gaining anything by adding a timing belt. With a 3:1 pulley ratio the torque at the screw is reduced to 1/3 that at the motor shaft. Looking at the torque curve of the stepper, the stepper torque looks to be about 1/3 at 500 rpm (maybe only slightly less), so considering torque alone, it seems adding a timing belt to reduce stepper rpm does not offer much if any benefit purely in regard to torque delivered to the lead screw and it’s just more complexity and opportunity for position error.

Stepping resolution seems to work for better in direct drive as there could be three times as many steps for a given stepping setting per screw revolution. I don’t gain or lose anything wrt to screw whip, wear, or load, with either because the screw speed is the same in both cases.
 
I would only be running these speeds cutting foam, and frankly, most of the time even that would be in the 100-150 in/min range.
Now my existing machine rapids at 650in/min. I’m not sure that’s a possibility for the new machine even though it would have two steppers and screws driving it, but I’m not inclined to value rapids speed highly because in my mind, if the machine is moving it should be cutting, not moving to a new position, at least the vast majority of the time. I figure that will be whatever max it can be.

So I’m thinking I may as well direct drive the screws with the steppers, but still may require a timing belt on the moving beam just for packaging to allow the beam to be repositionable. Am I thinking right here? Anything else I should consider in this?

I was a bit shocked by what decent quality timing belts and pulleys cost. It was going to be $150/axis just for a set of timing pulleys and belt. I could almost buy a gear box for that, and approaching the cost of import servos instead of closed loop steppers if they could be used with direct drive. -I know squat about servos. 

Best,
Kelly

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