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Topics - Tool-n-Around

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CamBam help (General usage) / Machining Polycarbonate
« on: November 23, 2022, 23:48:26 pm »
Hi all. Been a while but I’ve been busy with cb. I haven’t had to pay very close attention to feed/speed machining foam patterns but not the case here.

Looking for a little feed and speed guidance for machining polycarbonate. I previously made a post about another polycarbonate lid I made, but I’ll be darned if I can find it. Before I post the cb file, thought I’d just start with the piece I machined, and describe some of the issues I had, and see if I can get a nudge in the right direction.

The part is a display lid for an automotive air filter. The stock size is 21”L x 8”w x .5”t.

I’m seeing a lot of chip welding. I don’t have cut data for the bits, but in general they are carbide woodworking bits unless I say otherwise.

First op was the logo. I had machined it before on a previous project (also polycarbonate) with pretty good results. I set the lowest speed on my router (about 14krpm). It’s a single flute .031” ball nose cutter so it can fit through the narrowest regions of the letter pockets. The feed rates are 15in/min. The depth of cut was .020” and final depth .031. I cut a test plaque and thought it looked good. When I cut the logo on the actual part the chips melted/welded around the bit and scarred the surface around the ellipse. I’m thinking I need to back off to a smaller depth increment to help clear the chips and keep compressed air on the cut. The problem is the darn chips tend to hang on the surface edge like a stringy burr so they can’t always be cleared. Not sure which direction I need to go on feed/speed. I’m at low rpm limit. Coolant/mist is not really option.

The ornamental grooves cut pretty well.

The perimeter chamfer (.5”D double flute 90 degree vee). Depth increment was .15” and final depth .2”, 16krpm. It was a total mess with chip welding on the conventional cut side only. I did a .005” clean up climb cut and the chip welding switched to the waste side, and the part finish looked OK.

The filter gland is cut with a .5”D dish cutter. I didnt post a picture and it has some tool marks in part from the piece being inadequately secured (a screw in each corner and two in centrally in the part). I’m not too concerned about this because the gland turns visbly black when the filter element is installed and I'll never achieve optical clarity on my machine or without polishing.

The .25”D double flute spiral end mill perimeter cuts were a mess. The feed rate 60in/min, depth increment was .25”, and .35” cut width, 16krpm, which for sure was too aggressive for my router and probably so for my hobby cnc machine, especially in the initial two-sided plunge cut. I had a final .5" full depth finish cut of .010” which after observing the chamfer cut, I chose to climb cut. I didn’t post pictures because probably same issue here. The perimeter finish is not so great but why does climb cutting seem to be producing a better result?

I can post additional info as needed, but had to break the cb file up for tool changes and made in-process mods to those files so will need to update the consolidated file before I do so. I can probably salvage this part with some elbow grease but looking to do much better on next pieces.


CamBam help (General usage) / Some Qs on Imported CAD Files
« on: September 15, 2022, 19:49:28 pm »
Hi fellas. It's been a while. I've been happily motoring along with CB and more recently bought some CAD software (Alibre Design) to solid model my projects. As you may recall, I primarily use CB to machine polystyrene foam patterns for lost foam casting, primarily automotive parts.

Attached is a Camotics simulation picture of my first CAD modeled part. It’s an automotive intake manifold flange. I saved the solid model as an STL file for use in CB and that file is 15MB. When I import it into CB and set up several scanline 3D Mops to machine it, it becomes a 75MB CB file so I assume too large to upload here. The actual part is roughly 20”L x 3.5”W x 1.25”H. I simulated in Camotics and it looks ok. I haven’t tried to optimize the run time. This model is not filleted. The filleted version is even larger but I figured it wasn’t necessary since I use a 1/4D ball end mill as the cutter and it happens naturally without the filleted model.

To date I’ve done most of my CAD within CB and not imported objects. What is the preferred type of CAD file to import and use within CB? For the STL file, I have a bunch of options about the faceting parameters, surface deviation, and coordinate system as described here in the Alibre documentation. I have no idea what is necessary/adequate for my use in CB and probably chose excessive parameters. Any rules of thumb or advice in this regard?!alibre-help-v25/stl-export-settings

Ultimately, it seems this part would run much faster as a 2.5D part excluding the angled bosses, followed by some 3D MOPS for those bosses, but even with the run time, just running it as one surface would be quite attractive. Run time isn't me-time when you’re only making one or two parts :-)


Members Projects / Commemorative Carb Parts Storage
« on: April 09, 2022, 18:30:45 pm »
Hi all,

I use CB to make lost foam casting patterns. I make a lot of automotive and machine parts and receieve a lot of help from the forum. I have a several pretty sizable projects involving intake manifolds and custom induction systems for Inline Autolite carburetors. One of those projects is winding up, so I thought I'd make a couple commemorative gifts for the participants.

In a seperate project, I had made a number (14 !!) of working copies of 2-barrel version of the original Inline Four Barrel. So I took the work from that project made a few mods, and decided to make these commemorative parts storage kits for a couple of the other guys that have invested a lot in the project. They are aluminum cast aluminum present and appear to be a 2-barrel version of original carburator but actually store parts and related tuning tools. They also have a couple of additional features that mesh with their other hobby interests.

I did the personalizing by engraving the foam pattern as opposed to the casting. I think it may have been crisper to engrave the castng but the cast aluminum can be kind of gummy and load up cuttters, especially without coolant/cutting fluid and on fine details like this.

They're essentially done but I need to flock the inetrior storage compartments. Sort of like and Inline Four Barrel Autolite Carb and a Jewelry box went on a date and had twin love-children. They should be a nice conversation piece for their coffee table or man cave. I think they'll like them.


Members Projects / Automotive Scoop Adapter
« on: April 03, 2022, 15:11:30 pm »
I'm a lost foam caster and use CB to make lost foam patterns. Here's a recent project to make a carburetor to scoop adapter for a blown 41 Willy's Coupe. I'm still a bit of a hack when it comes to CB but I get by.


CamBam help (General usage) / Question on 3D Profile
« on: March 08, 2022, 02:24:59 am »
Hi all,

I was modleing some revolve extruded profiles and this one seemed like it would be ideal for waterline finishing. Why does the waterline finish method seem to ignore the bounding region and cuts the innner groove shown in the attached picture when waterline roughing or scanline methods do not?


CamBam Shop Feedback / Site Security Certificate Expiration?
« on: February 13, 2022, 22:35:21 pm »
I haven'y been on the forum for a couple days but every browser I try to access the site with starts screaming secutity warnings at me. https is displayed as https in the forum address line and I can't navigate the forum without getting kicked back to the security warnings. Anyone else having that problem?


Members Projects / Custom Automotive Timing Cover
« on: February 05, 2022, 23:44:25 pm »
Hi all,

I'm a lost foam caster and have been using Cambam to machine polystyrene foam patterns for evaporative casting. This pattern was machined in several pieces and assembled. Attached are a couple pictures foam pattern and resulting casting, and a YouTube video link describing the project.


CamBam help (General usage) / Machining Logo on 3D Surface
« on: December 15, 2021, 17:26:05 pm »
Hi All,

I was experimenting for another potential project that would require machining a relief on a 3D surface. I made a shallow sperical surface using revolve extrude and then projected the logo onto that surface. I just used a rough and finish waterline to machine the spherical surface but per David's recent tutorial, realize a cmbination of waterfall and scanline near the top o fthe dome will be better. -I can work on that.

I'm having trouble figuring out how to cut the logo into the spherical surface at a given depth of cut below the surface. Do I need to define a region below the surface at depth of cut? What is the best 3D profile method for the logo? See attached.


CamBam help (General usage) / Nesting and Copying to Point Lists
« on: December 01, 2021, 20:05:42 pm »
(Hopefully) Quick question regarding nesting and copying to a point lists, after having moved the machining origin. On the attached example the machining origin has been moved to the lower left corner of the stock but the component features are centered at the XY origin. The nesting was applied to a point list but the nested copies appear outside the stock (which is offset) and simulates off the stock. Is this because the stock and offset has only been specified at the Machine layer and not the corresponding Part layer for nesting?

Similary (but not in the attached example), I have used the the copy to point list plug in, and the copied objects are offset from the expected position by the (moved) machine origin displacement. Is this a similar cause/issue?


CamBam help (General usage) / Apply 4th Axis or Not?
« on: November 28, 2021, 20:35:19 pm »
I’ve been asked to make a scale copy of this clock tower (see picture). It will be a trophy and likely a bronze casting from yes, a lost foam pattern. I broke it into two sections for modeling and machining. I could have left it as a single piece but at 16”+ long it gets a little flexy.

The clock head was straight forward 2.5D. I have a quartz clock movement that resembles the original and fits in each side of the opening. I attached the CAMotics cut file. I would have preferred a more interesting font for the graphics but the very small size and embossed text made me settle for what I have.

I had three different thoughts on making the base and I’d like to invite some opinions on them and their feasibility. I divided the base into three sections as in the CB file layers. The lower square section is straight forward 2.5D work on each side. Just needs to be indexed 4 times at 90 degree increments. The rest is where I’d like the discussion.

For the center or what I call the pyramid section (see attached pic), I thought I’d either use the plug in for inclined/curved surface, extrude the equilateral triangle into the inclined surface or just exclude the triangular region as a region. Then index and repeat on all four sides. Might be easier if it was modeled outside CB and imported…..but this is a CB exercise. Might be able to extrude surfaces in CB too.

I read all three pages of threads with 4th axis in the title so am aware of the CB limitations and various work arounds.

My first thought was I don’t want to put a lot of effort into 4th axis work for one part and thought I’d just manually rotate the part and manually issue G-code commands for what (with 3 tools changes) were mostly just plunges and couple lateral moves. The tapered part of the pillar has 12 flutes @30 degrees that would be cut with 1/8” ball nose. I could angle the fixture for the tapered portion and flutes. -Not very studious or stretching. 
But I do have this cheapo 4th axis, and in addition to xyz, do have an A axis on my controller. So I could try my hand at just manually writing code for the plunges and moves but also code in the A-axis which is just spinning and indexing. Could also tip for taper flutes if need.

Then I was wondering if there was a way to vary the Z-depth of cut while moving along the x-axis (Y axis fixed on centerline) with A spinning or indexing. I thought the latter my require a surface thus the revolve extruded pillar. That could be done will a combination of a small end mill or may just the end mill will with fine steps. What say pros?


CamBam help (General usage) / Still Learning. Some Recurring Issues
« on: November 10, 2021, 19:08:59 pm »
I broke my ankle so am laid up. I’ve been writing a pile of CamBam programs and thank goodness otherwise I’d be going out of my skull stir crazy.

Been downloading plugins and trying/learning all kinds of different drawing and machining ops with success. The following is probably related to (my) poor CAD practices but there are a few problems that seem to recur and consume a lot of my time. Here’s an example (see attached cb file). I was just enabling/disabling the various primitives and machine op parts to troubleshoot and produce th ecomments below.

As opposed to fixing this example I’m really just looking to learn and correct the error of my ways so I don’t keep doing it.

If anyone has advice or comments, it is much appreciated.

Pocket 1

The intent was to relieve the surface between all the selected primitives, but I get an “unclosed shapes in pocket ignored” message and tool paths don’t generate. By eliminating the various primitives it seems the offending items were primitives 8 & 9. These were created as poly rectangles and later converted to polylines, so I’m relatively certain they’re closed and the polyline points appear at the corners. But, one of the sides is coincident with a line on Primitive 10. This situation comes up a lot for me, that being where I have to create geometry for a different height cut that is coincident with other geometry. Is this what is causing the problem and Why/how to deal with it?

Pocket 2

So I eliminated 8 & 9 and it runs pretty much as expected except when I run a Camotics simulation of this part (pocket 2 only), the sim shows the surface relief cuts piercing through the entire work piece as opposed to just showing 1/8” depth relief cuts in the thicker stock. At the Machining level in the drawing tree, I set the stock size and offset. I did not repeat the stock size in each part because I thought it defaulted to the Machining level data. I messed around with the stock surface setting but it didn’t seem to matter. Why can’t I exclude 8 & 9 from the relief cut?

Pocket 3

This one had me scratching my head. It is simply supposed to make a pocket relief between 10 & 67. But is ignores 67 with the message that “unclosed shapes in pocket ignored”. 67 sure looks closed but the polyline points are different at each end. Is 67 indeed unclosed? I tried cleaning and removing overlaps. It just produces an identical duplicate polyline. Which one is clean/overlap removed? The original one or newly created one by the command. It doesn’t matter which I use same result.

Pocket 4

I created some duplicate/subset geometry (11) to try to isolate/address the problem, but when I try to pocket 11, 8, it still ignores/does not exclude the rectangular region, but I do not get an error about unclosed shapes being ignored.
Ford Logo

Never mind this. I imported as a DXF from a set of sample files I got somewhere. It seems runs ok as far as producing tool paths but I think I need to clean it up and reduce the number of arcs/points on the polylines because it takes longer to generate tool paths.


CamBam help (General usage) / Incomplete Profile Tool Path
« on: November 05, 2021, 21:24:46 pm »
Hi all,

Been happily using CamBam for a while now and find myself stumped on a small project. Attached are two files. They are for the top and bottom side machining of an S-shaped linkage arm with a S-shaped rib and three bosses. The file called "Bell Crank Bottom" was created first. The tool paths generated fine on that one. The file called "Bell Crank Top" was created from the previous file with a numeric move (rotate) to mirror the part for cutting features on the opposite side. For some reason, when I try to generate the rib profile on Polyline/primitive 126 on the "Top" file, the profile cut is not completed on a segment of that polyline even though it appears to be closed and worked fine in the previous file. There is a roughing profile and then a finish profile on that part that was intended to include a fillet at the bottom of the rib, but neither profile shows nor simulates as complete. Tried cleaning, eliminating overlaps, etc, but no joy. Stumped. What did I do?


CamBam help (General usage) / Cant believe this one has me stumped.
« on: August 25, 2021, 19:43:23 pm »
Seems like the simplest program possible so after running a half dozen parts successfully, a bit humbling to be shot down by this one. It's just surfacing a 24" x 12" spoil board with a single polyrectangle and pocket MOP. The program simulates and appears to run fine but doesn't complete the machining even though it always reports program completion in the message line.

Tried two similar programs but same result....program finishes but the pocket isn't completely machined. Oddly, it seemed to surface a little more of the board when I ran it successive times but never completed, and the portion that was machined wasn't centered. The post processor is the grbl post Dave B modified for me. I didn't try another post.

Scratching my head.


Installation Help / Maintaining Multiple Instances of CB.
« on: August 11, 2021, 13:37:16 pm »
I have a dedicated computer in my shop and another I spend most of my time on. As far as cb, the shop computer is primarily used to run the CNC machine and the other to draw and create files. My administrative skills are modest so I was just wondering what is best practice for maintaining two separate instances of CB.

As far as various cb settings, I could see how I may actually want different settings on the shop machine, so my question is primarily in regard to plugins. I figure I can just keep a running file of all the downloads to keep track of what has been installed over time, but given the different installation procedures for various plugins, is there anyway to replicate all plugins on another cb instance other than installing them one at a time?


CamBam help (General usage) / Second Post, Second Project, Some Qs
« on: August 10, 2021, 02:46:20 am »
OK, so here’s my second cb project. It’s an air filter base and lid for the same automotive induction system in my first post here:

I’ve made similar oval filters and cut the polystyrene patterns with hand guided MDF templates on a pin router then cast the filter housing in aluminum using the lost foam method. On this induction system the carbs are too close together for separate oval filters so it requires a single filter for both. The four attached files are the (mostly complete) air filter base and lid. There are a top and bottom to each. I have a couple questions around two-sided machining, tool changes, and tool paths for certain tools.

If you look at the files, you’ll see I put four registration holes in the corners. I was going to mount registration pegs on the waste board and use them to locate the stock while successively running the bottom and top side programs. Whether with registration features like this indicating or other positioning aids, is this how two-sided machining is typically done?

I loaded the GRBL Machine plug in but had to disable/ignor the M6 tool change function because my files wouldn’t run. I only have a router with collet. Is M6 tool changing just for CAT like tooling with defined tooling attributes? Gary was kind enough to recommend this method in the link in post #72. Which I understand.

I need to make some tooling libraries but other than diameter I’m not sure CamBam is really recognizing tooling attributes. Does it? The topside of the lid requires three tool changes. ¼” bull nose, ¼” end mill, ½” dish cutter.

I’d also like to chamfer the perimeter of the topside of the lid with a ½” diameter 90 degree Vee tool. But it seems CamBam doesn’t drive the tool path off the center of the v-point, but treats it as the outside diameter, even though it is designated as a 90 degree vee. Is that correct? I figure I can either mis-state the diameter and/or the depth to get the chamfer I want but doesn’t seem right. What is usual practice?


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