[Fatboy]

Hey, that's great news!!!
Now let's see some action out of that machine.

Fatboy

[nego_0]

yes i cant wait!

[Fatboy]

We'll look forward to seeing some sawdust soon...just don't do what I did yesterday.

I offered to make a buddy a no parking sign for his shop. Didn't take long to pocket a 16" X 24" sign with 3" lettering. Then I noticed that I spelled the first word wrong (VENDER). As a joke I showed it to him and said that I was going to make it over, he kept telling me that it looked fine until I told him that vender is spelled V E N D O R!!! His friend stated several times to just cut out the "E" and put an "O" instead, he didn't understand how the letters where created and that it only took 20 minutes to cut it. Finally I made my point by breaking the sign in half.

BTW: I've been using mobile home door skins for years to make signs. My buddy saves them out of the dumpster for me and being masonite the cuts are crisp and clean. Most are 84" X 30" and thickness is generally .120", I pocket at .070". My brother's coffee shop is full of signs that he wanted, however, I got tired of paying for the shipping. They also hold up well outside if sprayed with a cheap clear coat to seal them.

Fatboy

[nego_0]

I moved, so my machine has been down for a while a long while. Its back up and running and im doing real cuts now. I found a problem that bothers me. when i cut a circle its off by a bit a 16th or 2. i think its my love joy couplings deflecting when the stepper turns. does this sound correct. and is there a way to fix it.

[Fatboy]

Welcome back!!!

I had that problem with my lovejoys too and thought about deleting them. My first crude homemade machine didn't use them.
However I tried running a layer of tape around them and wow what a difference. The machine even sounds different.

It's easy to start the tape and then jog the axis while holding the roll to wind it on. The only thing that I'd do different is not use black electrical tape (at least the cheap stuff) as the adhesive is messy after awhile.

I cut a couple of signs for my grandkids on Thanksgiving, first time in months that I've fired the machine up. I've waited all summer for it to get cool and even when it did I just can't get motivated to do much.

Fatboy

[nego_0]

Hey!! how you been. So the tape compresses the rubber grommet keeping the back lash at a minimum? I pulled a ton of back lash out tonight and did a pencil test on the spoil board and wow it was perfect circle. but when i get a cutting load on the router i know its deflecting. Matter of fact i can pull on the bit and see deflection. Any ideas with that. I fixed the coupling a little by compressing them into one another. They are so tight now that the almost seem to be bulging out.

[Fatboy]

The tape serves to connect the two hubs together so that there is no play (backlash) between the hubs and the spider. I tried the spider smash too but couldn't get the results that I was looking for, the tape really helps.

I also tried putting strips of tape between the lugs and the spider but it's a pain getting the coupling back together again and the results weren't that great either.

Keep in mind that (if you're like me) you'll spend as much time tuning, tweaking, and modifying your router as you spent building it. I'm thinking of a sliding knot system on the gantry for mine. I already have a 4th axis rotary setup made out of an old Craftsman 6" lathe... Speaking of lathe, I've been collecting parts to convert a small one to cnc. I have the steppers and will need another driver kit from HobbyCNC. The biggest challenge is the different axis designations, they seem all backwards to what I'm used to.

Mach3 has a turn program that I've been playing with and there is LazyTurn but it's about like LazyCam in usefullness. Luckily there's other programs that are fairly cheap.

Well, keep up the good work and keep us posted on your progress.

BTW, still at Langley? Or did the move mean a transfer?

Fatboy

[nego_0]

Still at langley. Im never gona leave the pit lol. Im gona try the tape thing it sound like a great idea. If i can pull the wip out of my X axis im gona be in good shape. i get little vibration at 50ipm but at 75 it as the gantry gets to either end it begins to shake. imm going to have to post a video of it for ya. Today im going to make a calabration drawing to see jut how bad it realy is.

[Fatboy]

I think that everyone has had a problem with the X axis whip. One of the issues with a long lead screw, especially the smaller diameter ones.
Higher feed rates will produce more whip, you have to find the trade off for your machine as they are all different. Last summer I spent hours trueing my lead screws in the big lathe using a dial indicator. This really helped the Y & Z axis but the X was fine for a while and now it has a little shake back in it again. If you run an X axis straight cut (about 12") you will see a rough pattern in the Y plane. Try it at diffeent feed rates to see how the roughness changes. I only see this pattern on straight cuts and it is easily sanded off.

Pick a feed rate that is a trade off between shake and the need for speed.

Also, the angle iron gantry side modification may be just the ticket to help correct the shake in the Y axis....maybe I'll put that on the list next.
It stiffens the gantry...I should do this today. Maybe, well I'll have to think about it some more. Besides, now I have to go search for it again, I think it's in the Modifications thread.

fatboy

[Fatboy]

Ok, I looked up the mods, actually it was easy to find them, they were the first couple of posts in te Mods section.

Check out video #4 on CNCJay.com
In fact watch all the videos, 1-4 for the router.

[nego_0]

yep if i stiffen up the gantry im sure i will be a lot better. I ran my test and it turned out well.. i want to build a plotter pen today but as far as i can tell im looking good. i do see som rounding on square corners. Not sure if thats the pencil deflecting or not gona give it another go. my circles were dead on.

[nego_0]

ran the machine at mutiple feed rates 25imp is nice, 50 is bad 100 is horrible. Its all in my X axis im i know its because of the crappy drill job i did when building the machine. i had a drill press with lots of wobble. so i guess what i can do is cut new parts at 20ipm and redplace and see if that pulls out the whip in my x axis. I built my own plotter pen with dual springs for constant force and it worked great ill post it up tonight on how i did it for free! After the parts are cut i know i can use hard couplings! yaaa!!! :cheers:

[Fatboy]

Glad to see that you are making some progress!!!

I gave my machine a 2nd birthday party today and gifted it an angle iron gantry brace. But when I looked at the right gantry side I was shocked to see that the lower half was bowed outward and the bottom box was pulling apart. I know that early on I may have over tightened the gantry and worried that this would happen. This is the only place that I didn't install 1/4" all thread brace rods.

Soo...I'm going to add a couple of bracing rods and then cut a whole new gantry, and while I'm at it I might as well cut the rest of parts to build an entire machine. It's going to be a lot easier this time because I can cut just about everything without indexing the larger parts as I had to do on my old machine. Plus I won't have to figure out all the dxf's, nesting the cuts, and figuring out the depths of pockets.

Meanwhile back at the farm, What pipes are you using for the X axis? All my pipes have spiral ridges that impart a little shake into the gantry as it travels. I never looked at it as a problem, now I realize that it can be better. Adding the gantry brace to the left side helped quite a bit but it's still there. I'm running at 90ipm feed rates which is my summer rate, during the winter I can get better than 100 without problems.

I've been composing this post for over 4 hours now and things keep coming up so I'll have to give it up for now.

Fatboy

[Fatboy]

Mods, Mods, and More Mods....

Since my last post I've added two threaded rods to the bottom of the gantry and added a moving knot system on the gantry.

The threaded rods really straightened things out, in fact I dropped my plan to recut a new gantry. Did the moving knot tonight and it works well, I believe that it just about eliminated the X axis shake that we were experiencing.

If you decide to do the mods now is the time, don't wait two years like I did. They are all worth while and well documented.

Good Luck
Fatboy

[nego_0]

Post some pics im interested

[Fatboy]

Post some pics im interested

Will do tomorrow!

[nego_0]

Been a long long time. But i cut my first real peice today for my RC plane F-22 looks great to me.

[nego_0]

So i was able to work on some stuff today and ran in to a funny problem. I was cutting parts to make a cable chain. The looked preaty good but i could see som rounding of corners on 90 degrees and my circles must have been off because they did not fit in there holes with out some sanding. it seems i may have either a router bit that is not .25" or i have some back lash maybee? I was cutting .25" mdf at 3 passes and im shocked to see that kind of problem. Should i try and tighten up the machine or is there a way to compinsate for this?

[nego_0]

your 3 pics did not show up. I did do some circle poket test and found out i was way off! did the back lash comp and had better results im .002 off from my x to y axis. my y motor makes a loud BEEP noise when it starts. i set my comp to 100% and my general step movment to .005 sec. like i saw in a youtube video. Im gona try cutting some parts agian and see if they fit together now. I aslo found out that my sears router bit is not a .25 its more like .245 lol. I guess cheap bits are not the way to go. Also im using MDF so im not sure if im getting the best readings from my Micrometer. [ame=http://www.youtube.com/watch?v=A27nOkTFYDY]Mach 3 Backlash Compensation - YouTube[/ame]
I was wondering in the back lash setup what is the A B C for? my x and Y are close but my transitions are still of by .012 or so? LOL one more thing does your steppers get hot mine get warm but after an hour of running i can barly hold them?

[kbisswanger]

If you are using Mach you might check the CV settings. Sometimes this causes the issues you have described.

Biss