I see some posts about "where are the newbies?", etc, etc. I've been on the forum for a while, made a few posts, but I'm finally actually going now so I thought I'd start this "blog" or running journal. I should have started this about a year ago, but I'll do what I can to get caught up to current time.

First, if this is the wrong forum, please let me know and move it.

A little history on me. My online nickname just about everywhere is Quicker. I spend 90% of my online time at http://theprofilebrotherhood.com/forum where I am one of the site admins. When I'm not on that site I'm on RGroups or the Flying Giants. I own and run http://kalteisen.com where I design R/C airplanes...mainly 3D electric planes. I've had a number of airplanse produced as ARFs, but due to getting many designs stolen by Chinese factories I focus on kits now. Ever rising laser cutting fees prompted me to want to buy a laser cutter, but I quickly realized this was out of the ballpark so I decided on a cnc router to make my kits.

I tried building one from scratch, but I have kids and a life and the parts just sat in the garage. I did buy a controller and a bunch of steppers off ebay, but that controller turned out to be a piece of junk. Search here and you will find that thread. I finally settled on buying a built unit from a great guy called cardin1 on ebay. His name is Ricardo Mendonca and he has been great to work with.

OK, that out of the way the next post will start to get closer to current time in my saga.

Q

My desire here is to cut parts for my kits, which are mostly balsa that is 1/4" thick or less. I have some 1/16th ply in them, but not much. After doing a lot of reading I settled in on a 1/16th tool in my Dremel. The table came with a RotoZip, but I am also very concerned about sound levels. I'm going to try a brushless airplane motor as a spindle at some point.

The table I bought came with a full copy of Mach3 and I'm using TurboCAD to draw the parts. When I first started playing with all of this I learned that Mach3 could import the DXF from TurboCAD and it would convert it to gcode and I was running simulations on my laptop. pretty cool. I also ran a program called CNCSimulator for almost a year playing around before I got my own CNC Router.

I was familiar with the process of drawing parts to be cut out because I have been sending my files out to a laser cutting service for nearly 3 years now. I figured this would be simple.

When I got the router Mach3 had evolved into a bit more complex application and it now used something called LazyCam to import the DXF files. This looked cool because it could set cutting speeds, offsets, etc, etc, but I was lost. I now knew the chain here was:
TurboCAD -> LazyCAM -> Mach3 -> finished parts
but LazyCAM seemed odd and it doesn't seem to always do what I want.

On the ProBro site I started chatting with a guy named jspencer who also had a CNC router and was messing around with cutting balsa. He is in the same position as I am with a bit more knowledge, so he's been lending a hand. He got me going with LazyCam and pointed out that most functions are tied to lead-ins. If I want to set an offset I have to turn on lead-ins. OK, so I turn on lead-ins. The only problem is they are all over the place. My files are pretty complex with lots and lots of parts on each sheet of wood.

I spent the last 2 weeks messing around with LazyCAM trying to get the offsets to work right, but it's VERY frustrating. Half the time the tool is cutting on the wrong side, not doing what it said it was going to do. jspencer confirms this on his router.

I tried just setting the lead-in length to 0, but it still puts little notches in the wood. I have attached a pic of the latest cuts. This just is not going to work. Also, I put cut-outs in the parts to hold them in the wood for shipping. I don't want the parts floating around. The kit builder just uses his knife to "pop" the parts out of the sheets. LazyCAM's toolpath is all over the place. WHAT A MESS!!!!!!! Maybe in the future LazyCAM will be OK, but this is one buggy pice of software right now. To be fair, I know it's early in the development cycle.

I remember way back in my early readings finding a program called ACE that would generate gcode from a DXF. It does not create offsets or cutting speed settings, but I thought I might be able to set those by hand later so I tried generating some gcode with it and comparing the toolpath with that from LazyCAM.

WOW!!!!! it was WAY more optimized and the code was 1/2 the size. LazyCAM's was over 800 lines and ACE's was only 400.

Look at the pics to see.

Q

In the above post I attached a pic of some ribs I cut using code from LazyCAM. Not good.

I was very happy with the finish of the cuts, though. I'm using some cheap micro bits from Harbor Freight. You can get a set of about 15 or so for around $7-$9. They range from the thickness of a hair to just over .0625. They seem to be mix-n-match. Those ribs were cut with an .030 bit with my dremel at full speed and moving at 12 IPM. Not bad. The wood is 1/16th balsa so I tried stacking 2 sheets to cut 2 at a time. I had to drop the speed down to 9 IPM because I broke a bit, but it worked. That still figures out to be 18IPM since I'm cutting 2 sheets at a time.

The .030 bits do not like the 1/4" balsa though. I broke 3 bits even at 5 IPM, so I'll move back to 1/16th bits for that.

Q

As I'm getting caught up here I noticed I forgot a few things that I learned. Mostly around offsets.

When I was first starting I was very confused about how I would know where 0 was on my table for X/Y and Z. I quickly figured out that at least for me, I manually jogged the table to the lower left and then touched the tool to the top of the material. I would then zero out the X/Y and Z axis in Mach3. In LazyCAM I would tell it to then go negative z down the thickness of the material for each cut. If I was cutting 1/4" wood than I would tell it to go down -.25. Zero was the top of the meterial.

As I am now switching over to ACE, I find that it treats the BOTTOM of the material as zero. OK, that's an easy switch. I will just jog over and bring the tool down to the bottom of the material on the side of the piece of wood and then zero the Z axis. I could also just do a global search and replace for the gcode that moves Z to 0 and replace it with -.25, or whatever I'm cutting. I think I'll just zero the table to the bottom of the sheet of wood. It's easier for now.

When trying to do offsets I 1st tried to do it my my CAD program thinking that I would then not have to mess with a CAM package to generate gcode with offsets, or mess with tools in Mach3, etc. Bad idea. I did get 1 of my airplanes totally setup with offsets in CAD, but it quickly hit me that I was locked into the tool diameter I chose and I decided it was too big. Now I had to go back and redraw all the offset lines. Even with TurboCAD's offset command it took me a week.

Note to self: This is stupid. Setup the tool table and use offsets in gcode.

I went into Mach3 and put my tools into the tool table. This is simple. Just give your tool a description and set the size. My first one was the .0625 bit I had, so it's tool #1. Cool, now I can make some gcode and select that tool. I saved my CAD file as a DXF, then used ACE to convert it to gcode. change the file extension from .txt to .tap.

Open the gcode in an editor. I use Crimson Editor, but any text editor will do. I added this as the 1st line to the gcode program.


M6 T1


That selects Tool #1, my .0625 tool. How did I learn that? I looked over the gcode that LazyCam had generated and it's not hard to figure out.

Offsets when I have more time to get caught up.

Q

ACE does not need to use the bottom of the material for Z=0. Are you entering the depth of cut as a negative number? Haven't looked at it in quite a while, but you enter negative numbers for the cutting depth.

As for offsets (cutter compensation), you'll need to add lead ins and lead outs and use G41 and G42 commands.

I think my copy of ACE is old. I have no option for setting Z. I'm going to look and see if I should download a new version.

Q

You need to double click on something to get to the window to set the depth, but I don't remember what exactly. Layer perhaps?

DOH! :rolleyes:

Found it.......

Q

By far the cleanest cut I've made were just made on a modified Dremel 2 flute down cut 1/8" diameter bit. Stock it's about 2" long and gravitates like crazy at my dremel's full RPM's so I cut it down to only a .25 cutting area and put it in at full speed on the Dremel. I was cutting at 20 IPM with NO hairs or fuzzies. The cleanest cuts I've made to date, except for the .030 bits in the thinner wood at 5-7 IPM. I think I could push that 1/8th bit to 30 or 40IPM just fine.

The downside is it's LOUD!!!!! My wife said she could hear it plain as day in the bedroom on the other side of the house. She can't hear the 1/16th and smaller bits. The flutes are huge on that 1/8th bit which I'm guessing is what makes it so loud. Totally not usable. It would make the neighbors upset.

I think my 1/16th bit would do the same quality if it was a down cut instead of an upcut. I was just watching it and you can watch the strands of balsa climb up the bit, then break off leaving hairs all over the place when cutting with the grain. When going cross grain the cuts are nice and clean.

I'm ordering a few different 1/16th bits (http://www.drilltechnology.com/router/downcut.html), like a 2 flute down and a diamond pattern. I like the .030 and .040 bits I have from Harbor Freight, but they keep breaking off unless I keep the speed down under 7-8IPM. That's like watching paint dry. It would take over an hour to cut a Skeeter 30 (http://kalteisen.com/?f=skeeter_30.dat) which is my best seller. The .06 bits that came from Harbor Freight cut well at high speeds, but since they are an upcut I get really bad fiber strands all over the place.

Q

Back on the subject of making gcode. I think jspencer's thoughts that LazyCam is best and designed for closed objects is correct. When I play around with my files and leave each part as a closed object it generates a nice clean toolpath and I can usually get the offsets to work right. Problem is that just won't work for me. I need to leave the parts in the sheets of wood.

On a positive note, I'm learning much more about the process by using ACE. For me it's much more intuitive since I'm a Unix admin and have a lot of programming experience in my day job.

Q

So far the best compromise in speed, tool size and clean cut looks to be the .0625. I ordered in a bunch of diamond pattern .030-.0625 downcut bits (http://www.drilltechnology.com/router/downcut.html). With my current .0625 upcuts I'm getting strands and hairs, but I can clean up the sheet very easily. The strands pull off and leave a very clean cut. It will work as a temporary solution until my downcut bits get here. The 1/8th bits are just too large, not to mention noisy. Even if it was quiet it's too large to cut out the notches for 1/16th wood spars notches and rib notches.

The guy at that company was very helpful and has many more diamond bits than what is listed on that page. He recommends coarse teeth over medium teeth for what I'm doing and also said downcut is the best. I ordered a few medium and a few coarse just to see what I really like better.

Here's a pic of the bones of a couple of my planes. These were laser cut, but you can see the type of work I'm doing. Everything is interlocking and the plane can mostly go together without glue.

Q

Hey Quicker,
This is a great thead. I'm a newbee and have learned a bunch about speeds, bits and software. Thanks,
Dave

Been a while. I've been busy at work and have not had a ton of time to use this. Back to the fun, now.

Man I was getting upset a few days ago. I was trying to cut all the control surface parts for the Edge 540 I'm working on and the gcode ACE was producing was crap. I was getting double cuts, crazy stuff, etc, etc. I checked checked and rechecked the CAD file and everything was snapped and no double lines. The reason I went to ACE from LazyCam was because I wanted little cut-outs to hold the parts in, and LazyCAM really gets confused while ACE produced such clean tool paths. Now, on the last 2 planes I've drawn ACE is making a mess of things.

Well, since this is not for a kit, but just for me, I don't care about tabs to hold the parts in the sheet of wood, I just want clean offset parts. Lazy Cam also does a cool thing where it cuts the inside holes 1st, then the outside stuff. It still doesn't always do the cut right and will cut on the wrong side of the lead-in but I can just go into the gcode and switch the g41 to g42 or the g42 to g41.

If I can just get past this issue of so much prep time for the files I'm rockin and rollin.

Q

Now that I'm not worried about the tabs to hold the parts into the sheets of wood, LazyCam is saving me a TON of time and it's generating good paths. It still does not always get the cut on the right side of the line for offsetting, so I have to run a simulation in Mach3 and watch the tool and manually set the proper offset command in the gcode file, but that's not a big deal at all.

It's crazy how on the Skeeter 30, ACE did such a good job of making the gcode, but now on everything else it's puking all over itself. I even redrew the ribs from scratch and it puked on them, making double cuts, going off into straight lines right out of the LE curves, etc. LazyCAM required that break the LE curves into smaller segments before it could handle them, so I did, but ACE still puked on that file.

Once I get a part so that LazyCam says it's clean I past that back into my master drawing. It "should" then be clean and snapped for any other cutter.

I attached a pic of the Edge 540 I'm working on now. It's wingspan is 31.5 inches with a target weight of 12-13oz.

Q

I agree, this is a great thread. I am just starting construciton on my machine and have watched the LazyCam video as I am going to use Mach3. I know it's in it's early stages but it's great to read your real world experiences with it. Will make it a lot easier for me when I finally am able to 'crank 'er up'.

Thanks for the posts Quicker.

BobL.

SInce you're using this for a business, I'd recommend possible taking a look at SheetCAM. It's only $150, but might be money well spent based on the struggles your having. Download the demo and give it a try. If you need more time than the trial allows, email the author and he'll usually give you an extension on the trial. Support is excellent through a Yahoo group, but he also usually answers question here very promptly as well.
www.sheetcam.com

I'll look at it.

LazyCAM is doing a great job, short of one major area that I really need/want. I need to leave uncut areas to hold the parts in the sheet of wood. LazyCAM just doesn't like it when I do that. It runs rapids all over the place. Other than that, it's doing a good job. I could just live with the rapids and go I guess.

Q

This is cool as heck and I'm having fun, though :cool:

Q

Q:
Is this possible?
1. Take a Closed dxf profile that you know works, and modify it to contain some short line lengths to represent your tabs.
2. LazyCam will process this file and the result will be a cutout without tabs.
3. Edit the g-code text. Find the cut segment for the tab, and add a z offset at the beginning and end of the tab segment.
4 Final cut should contain tabs.

I hope I'm not to far off base on this topic.
Dave
PS. I'm a newbe, and my thoughts above come only from reading this forum.

Back on the subject of making gcode. I think jspencer's thoughts that LazyCam is best and designed for closed objects is correct. When I play around with my files and leave each part as a closed object it generates a nice clean toolpath and I can usually get the offsets to work right. Problem is that just won't work for me. I need to leave the parts in the sheets of wood.


Q

That's an idea that I had, too. I might give that a shot.

Q

Wow. Learned something new. I'm trying to setup the files for a new plane and in LazyCam they look like crap. Leadins all over, disjointed, etc. Looks like nothing is snapped, but I have redrawn the sections over and over. Honestly, I was getting really frustrated and disappointed thinking this entire CNC router thing was a mistake. Setting up the files has been a major PITA.

Then, I decide to try grouping the parts. Let's look at a rib. The rib has a bunch of lines and a few arcs. They were not grouped together, so LazyCam was putting leadins on a lot of the joints. I would go in and make sure they were all snapped, but I could not get rid of them. I went into TurboCAD, selected the entire rib and grouped it together, then saved the file as a DXF again. Now when I load it in LazyCam I have 1 leadin for the rib and 1 leadin on each hole in the rib.

Perfect. Takes about 5 minutes to prep the file now. This is still without the tabs to hold the parts in. Still messing with that. I know a different CAM package would probably deal with them better, but I'm not ready to put out another $150-$200 right now.

Q

Quicker you really should download the demo of Sheetcam.

Reading about your frustrations getting good gcode, I reckon you will soon think $150 is well worth it. :)

And it costs nothing to have a look at it.

Greg

Hi Quicker...

For doing dxf-gcode you shoudl take a look at NCplot V2...

I'm using it and found it really good, so good that I bought a copy, which is saying something for a linux geek...

It does some cool interactive editing, and provides a very flexible dxf import tool.

It has 'chain' and sorting tools for the g-code conversion to get clean paths, and you can select the order it cuts the paths in.. Added to that is the helpfullness of Scott (The author) who is on this site regularly, and it's a winner...

(I'm not associated with NCPlot, just a happy customer...)

Nice models as well, I've got a small DIY router at the mo, and I'm working towards a larger one to cut model bits, so your comments on cutting tools has been good value for me. :)

I've temporarily solved my tab problem by just cutting the lines were I want the tabs, using LazyCam to make the toolpath and set the offsets, then run a simulation quickly in Mach3, finding the line where the tab starts and putting in a Z offset. A little tedious, but it works.

My shop time is early in the morning, sometimes late at night. Due to this schedule I have not been able to use my CNC router much because of noise issues. I looked at a lot of options and the best seemed to be to make an enclosure for it.

It did cut down on the noise a lot, but I want it quieter. I'm going to either lay a chunk of carpet in it or put insulation on the walls. Maybe both. I have a bunch of carpet left over from doing the basement, so I think I'll start with that. As it is it is quiet enough that I can use it in the morning and not cause problems.

Inside is a mess still. I need to finish routing all the wires and I need to put in more lights inside.

Some have asked about how I'm holding the wood down. You can see the raised platform that I made for 6x24 sheets. I have another for 12x24 sheets. I use clamps, or as you can see, the large paper clips. The raised platform allows me to use clamps all the way around the wood if I need. Usually I just put 1 or 2 on the ends, maybe 1 in the middle.

The dremel is working fine for balsa, but I'm looking for a good variable speed router now because I have a new airplane design where I'm going to be milling 1/4 and 1/2 aircraft ply. I'd really like to get spindle control running in Mach 3.

Q

Here's a quick shot of the latest plane that I prototyped with this. I've got it coming out as a laser cut kit, and in about 5 months the ARFs will be in stock.

http://kalteisen.com/

Length: 32.75
Span: 35.5
RTF Weight: 14oz-15oz

Recomended power system:
Motor: Torque 30T/980
Battery: 900mah - 1300mah 3cell Lipo

Q

Funny how things change. Mostly my point of view on this thing. I'm now not so worried about tabs holding the parts into the sheet of wood for shipping. I now see the elegance of LazyCam. I can quickly and easily lay out the parts as a solid object, prep it in LazyCam and by cutting in no time. My customers actually like the loose parts. It can take a long time to cut the parts free from the sheets. Now I just bag them up and they just need to find the part they need, like a jig saw puzzle.

To hold my parts down I'm now using a 3/8 thick sheet of balsa for a bed that I clamp down to the table. I then am using a light mist of 3M Super 77 spray adhesive to hold the sheet to be cut down onto the 3/8 bed. Most of the sheets that I cut are 1/16th or 3/32. When cutting a lot of parts, the sheets start flexing around, no matter how many clamps I use. They also will rise up in the middle. The only way I found to hold them is with the spray glue. The thinner stock, like 1/16th and 3/32 are usually doubles up, so I cut 2 sets of parts at a time.

I give each part a quick swipe around the edges with a sanding block to take the fuzzies off, and to take off the glue. It really does not take that much time. I then bag them, box them and ship them.

My 2 favorite bits now are the 1/16th diamond downcut pattern and the 1/32 diamond downcut pattern from here:
http://www.drilltechnology.com/router/downcut.html
jspencer was going to order from this other place to see how they look in comparison. I sent him one of my 1/32nd bits to check out.
http://www.mctinfo.net/index.php?act=viewCat&catId=17&PHPSESSID=bd2004819118c7d3813e6c4910778339

Q

I just ordered 10 of the .031 dia downcut bits. Thanks for the tip.

If you get a chance, I'd like to see some photos of your balsa clamping setup.

What feed rate do you use when cutting balsa ribs?

I really like the .031 bits. In 1/4" balsa I cut at about 20-25 IPM. In 1/16th, 3/32 and 1/8th I'm running 40-45.

I broke my last .031 bit a few days ago so I had to go back to the 1/16th bits to get a bunch of orders out. They are doing fine and do allow me to cut much faster. My 1/4" wood was cut at 45 IPM.

I'll try to get some pics soon.

Q

Very Cool. How do you get the "Skin" on the "Bones"? I am very impressed

The skin is heat shrink plastic covering with a heat activated adhesive on the back side, specifically made for model airplanes. Many different brands and different weights and colors.

For glow and gas planes, Monokote and Ultracote are the two most popular. Monokote is the oldest brand and probably the most used, but Ultracote is becoming more popular in the last few years because it shrinks better and the heat activated adhesive seems to be better.

On electric planes, weight is everything, so they have developed lighter covering. Ultracote developed Ultracote Lite, and other brands have popped up. The problem with UC Lite is it only comes in transparent and semi Opaque. Most want a solid color. Transparent planes are hard to see when flying. You lose orientation easily.

To get the covering on, you use a covering iron and a heat gun. Pull it as tight as you can, then seal the edges with the iron. Give it some shots with a heat gun and it shrinks up tight. Be careful, though. Too much heat and you melt a hole!

http://www.horizonhobby.com/Articles/Article.aspx?ArticleID=1472

http://www2.towerhobbies.com/cgi-bin/wti0093p?&C=QAA
http://www.horizonhobby.com/Stores/Products.aspx?StoreCatId=A&CatId=APC

Q

Hey Quick,
I haven't cut any ribs yet, but I've been wondering how well a 1/16in bit works in the tight spaces of a Spar cutout? It leaves a radius cut in what should be a square opening. Is the radius so small that its not noticed?
Dave


I really like the .031 bits. In 1/4" balsa I cut at about 20-25 IPM. In 1/16th, 3/32 and 1/8th I'm running 40-45.

I broke my last .031 bit a few days ago so I had to go back to the 1/16th bits to get a bunch of orders out. They are doing fine and do allow me to cut much faster. My 1/4" wood was cut at 45 IPM.

I'll try to get some pics soon.

Q

The balsa is soft enough that the 1/16th bit is fine, even for the rib cutouts. Push the parts together and they fit fine. Now, I'd much rather be using my 1/32 bits, but I'm out and I must get these orders filled.

Q

Quicker, Awesome. I started getting into RC aircrafts about a year ago, but it got put on hold when i moved to VA. I moved here to work for a company, Im a cnc journyman machinist. We make flight control devices for military and commerical aircraft. I just got my ParkZone, (i think it is) from my parents house.. its crashed and i got to get a new body for it, but once i get my Router finished, i think that making a body for it would be a really cool project. Thank you for the info. I greatly appreciate it. Keep up the awsome thread
Mike

You could try making a simple vacuum table to hold down your balsa. The vacuum would hold it in place while it's cutting.

Just a thought.

Wade

with a vacuum table, what happens when you cut too deep. I haven't figured that out yet.

I'm worried about losing too much vacuum. What happens when I cut a file like this attached one? I'm cutting so many parts out of a single sheet. The only good way I've found to hold this down is to spray adhesive it to a thicker chunk of balsa that won't flex. Right now I'm using a 3/8" thick sheet. These parts are cut from a 1/16th sheet of 6x24 balsa.

Q

Also, a lot of my parts are really small. I don't think a vacuum would hold them at all.

Q

I wouldn't hesitate to cut that out using a Vac table, especially if you are using a good vac pump. You place cardboard over holes that are not covered with your material. That gives you an even vacuum. If you holes are fairly close together (ie. 1/2 inch or 1/4inch) all that will happen is your pieces are cut out and stay put once they are loose.

As far as what happens if you cut too deep, well, you cut into the vacuum table. To circumvent that, you would have replaceable tops than can get cut into. When they are cut into too much, then you just throw them away. You could use your cnc router to make those throwaway tops out of cheap 1/4" plywood from Menards (or other store).

I'm not an expert, but have been doing testing for something similar, but with a much flimsier material than balsa.

Hope this helps,

Wade

can't you use hold down clamps and program around them?

Guys, I'm not complaining about my hold down system....I'm happy with the state of the system right now. A little 3M Super 77 and even my micro parts are held in place.

I tack the sheet to be cut to the thicker sheet of balsa, minimum 3/8" thick. I clamp that down to the cutting surface and cut the parts. Fast and simple and effective. The sheet that is being cut no longer bows up in the middle and everything comes out looking great.

Eventually maybe I'll try a vacuum system, but as of right now, it's not needed.

Q

Q,
What size balsa material are your glueing down? 6x36?

6x24

Q

Due to some family issues I'm being forced to sell the router.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290130702532

It's in perfect running order. Life is just getting in the way.

Q