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Re: Jim's corexy - 8 years ago

It was already pointed out to me, mistake when I measured wrong. It's a easy fix by moving the position of the bearings but I haven't done it yet. I'm just glad to get it working again. Corner brackets need to be cut down. It will be done the next time I remove them. CNC is still down. I sent all the bad servo drives back to Geckodrives for repair. Any work on the 3d printer we have to wait

by Jim Fong - CoreXY Machines

Re: Jim's corexy - 8 years ago

It's been a couple of weeks since the lightening strike. Still dealing with insurance but had some time to put in new stepper motors and drivers on the corexy frame. Haven't done much more than that yet. Another video moving a 635gram steel 123 block around.

by Jim Fong - CoreXY Machines

Re: Jim's corexy - 8 years ago

Just a little overwhelmed. Sitting in my upstairs electronics lab checking things over. Most of the lab equipment turns on. The lightening hit the rooftop furnace exhaust stack which is metal. Blew that to pieces. The energy traveled down to the basement furnace room area which happens to be where all my CNC machines/workshop lives. Most everything in that room is dead. Even some stuff that

by Jim Fong - CoreXY Machines

Re: Jim's corexy - 8 years ago

Bad news My house took a direct lightening strike today. Multiple computers dead, power supplies, multiple stepper and servo drives for the all the cnc's all dead. Even the 3d printer electronics is dead. Stuff plugged into network like hubs and raspberry PI's all got zapped. Cable modem dead, furnace heater dead. I don't even know where to begin. Atleast the house is still standing. Oh yea

by Jim Fong - CoreXY Machines

Re: Jim's corexy - 8 years ago

Ya I know, I messed up the when I CNC machined the part. Wrong measurement. Easy fix to move the pulley over more when I get a chance. The plates need to come off and have the corner chopped off too.

by Jim Fong - CoreXY Machines

Re: Jim's corexy - 8 years ago

Another video, this is a little faster. Ran the software config and changed some settings. What a pain that was. None of my laptops had a DB9 serial. Had to dig out a old desktop to connect and run the config program. Found out the programmed current was set at 60%. Bump it up to max. This gave the motors higher acceleration without stalling. Grbl1.1e 40,000mm/min (666mm/sec) speed 10,0

by Jim Fong - CoreXY Machines

Re: Jim's corexy - 8 years ago

It does 45 and 135 at the same speed too. Hard to say if it is actually reaching those speeds, I did double the acceleration and it looks the same. I may be hitting a ceiling with the grbl software and it's step pulse output capability. Smoothie firmware will do 99khz step pulse rate vs 30k that grbl does. I'll have to install the Cohesion3d board later and do some more bench testing. Really

by Jim Fong - CoreXY Machines

Re: Jim's corexy - 8 years ago

First movement, about 600mm/sec. Using grbl1.1e to test until I figure out how to configure the cohesion3d smoothie board for corexy. This is the max speed steps per second for grbl and Arduino uno board. Edit. 4000mm/sec^2 accell 10microstep 24volt PS Arduino UNO Grbl 1.1e

by Jim Fong - CoreXY Machines

Re: Jim's corexy - 8 years ago

Stiction. That's the term I was trying to remember. i think it would be a issue.

by Jim Fong - CoreXY Machines

Re: Jim's corexy - 8 years ago

Three lifting points would be nice but I don't think I can find another matching Kerk leadscrew cheaply. I bought both for $30 or so a long time ago. They are pretty expensive new, Hopefully using profile linear rails will keep it from wobbling if properly mounted. I actually have a choice between 15mm wide Star/Rexroth linear rails which are longer than the 20mm THK SR rails. The Star/Rexrot

by Jim Fong - CoreXY Machines

Re: Jim's corexy - 8 years ago

DD, I have to defer to your experience than. The single linear actuator would of made it really simple, just mount it to a vertical piece of extrusion and you're basicly done. I now have to machine two identical linear actuators using the shorter linear rails and antibacklash kerk lead screws. It's going to take longer now, plus ordering couple more pulleys/belts to drive it with a single mo

by Jim Fong - CoreXY Machines

Jim's corexy - 8 years ago

Building a 3d printer for my home. I have access to several at my brothers workplace so it hasn't been a priority to have one at home, until now. 400x450mm travel using 20mm nsk/THK linear rails. 80/20 1020 extrusion. I have built several CNC machines so no stranger to linear motion and automation. I can machine any parts on my lathe or mill that is required. My question is that I have this b

by Jim Fong - CoreXY Machines

Re: Linear guide carriages interchangeable? - 8 years ago

Bearing carriages from a different manufacturer will not fit your rail. The linear rails all have different cross section profiles. RSR1 sounds like it is made by THK. I have a few THK RSR 9mm linear rails laying around. IKO sells replacement bearing carriages for your rail. If you are lucky you can find them in eBay. You need to make sure it is the exact same model number. There are some ra

by Jim Fong - General

Re: NEMA 23 steppers - 10 years ago

QuoteTraumflug QuoteJim FongTelling someone that all nema23 motors will run at .5amps may not be necessary true. It is. Driver limits are not a motor limit. And running into driver limits gives the same result independent of the size of the motor connected. NEMA17 steppers would behave just the same. Accordingly you can say that a particular driver is not capable of running at low currents, but

by Jim Fong - General

Re: NEMA 23 steppers - 10 years ago

QuoteTraumflug QuoteJim FongI had a 4amp nema23 that I was testing and was running rough. It wasn't until I bumped up the current to about 1.5 amps did it start to run smooth. Most likely a problem of the stepper driver: QuoteJim FongThere is detent torque and mass of the rotor that may affect the running of the stepper at very low current. Friction in the bearings?? Friction in ball bearin

by Jim Fong - General

Re: NEMA 23 steppers - 10 years ago

QuoteTraumflug QuotevulcanrdJust make sure that the NEMA 23s don't require a lot more amperage than the Pololus can output . Steppers don't "require" amperage. A stepper designed for 3A works with 0.5A just fine. You won't get the specified toque, of course, but half the torque of a strong motor might be more than full torque of a smaller one. And running steppers at less than the maximum curren

by Jim Fong - General

Re: Nema 17 - stronger motor alternative - 11 years ago

Got around to testing a pololu drv8825 stepper driver on my test bench using a automation tech nema17 stepper motor. This is a 1.5amp 76oz-in 4.8mh nema17 motor. Using a 12volt power supply, I was surprised that I can get the motor to spin over 2000rpm. Driver was set at 8 microstep mode. Im not sure if a Arduino can output a step rate that fast so I used a external Tektronix frequency pulse ge

by Jim Fong - General

Re: Nema 17 - stronger motor alternative - 11 years ago

QuoteA2 Gantry Type Machine Building Lots of good info can be found here for routers. QuoteJim Fong I use the 276oz-in stepper from automation direct and gecko drives for my gantry router. Does 300ipm rapids. Stay away from the bigger 400oz-in steppers unless you can afford a higher voltage power supply and very good stepper drivers. The smaller 276oz-in can spin pretty fast, a big plus if yo

by Jim Fong - General

Re: Nema 17 - stronger motor alternative - 11 years ago

QuoteArnold Hi Jim, I am thinking about at final 2x1,5m work area. I would like to cut just boards from wood, plastic, maybe aluminium. But firstly I want to make a little cnc for tests. Frame and linear rails will be aluminium, threated rods m8. Everything must be cheap so I dont plan to use some special components. I dont want to safe money on motors because I will sure make upgrade, so that is

by Jim Fong - General

Re: Nema 17 - stronger motor alternative - 11 years ago

QuoteArnold I would like to try CNC so that is why I dont want to use nema 17, no moving by belts, but threated rods. Not a expert but I've built several CNC's over the years. Don't rush on buying the stepper motors right away. It's best to look at the overall design first. These are some of the questions that need to be answered. It will help decide on what size stepper to buy. Like I said bi

by Jim Fong - General

Re: Nema 17 - stronger motor alternative - 11 years ago

QuoteArnold Ok, so could I use these kind of motors with actual setup for casual reprap with arduino using nema 17: and if yes, what will I need to make it work properly ? These are rather high inductance stepper motors, 6.8mh when wired up bipolar parallel at 2.8amps. They would not run very fast speeds unless you have a high enough power supply to drive them, probably greater than 36volts

by Jim Fong - General

Re: Nema 17 - stronger motor alternative - 11 years ago

Quotecnc dick You said that there has to be many people that use external stepper drivers for 3-D printers I haven't found any if I remember right lobo CNC did on have their first 3-D printer and they have done away with it. If you find any case post a link or pictures video any thing. Anybody that is using external drivers seem to be running Mach 3 for their printer Here you go look up Builders

by Jim Fong - General

Re: Nema 17 - stronger motor alternative - 11 years ago

BTW I just looked up the minimum step timing requirements of a drv8825 chip used in the pololu driver and they are higher than a gecko step driver. If that works with arduino ramps board there's no reason a gecko driver won't. And certainly no problems for the much faster Parker drives that I also have.

by Jim Fong - General

Re: Nema 17 - stronger motor alternative - 11 years ago

Quotecnc dick Okay I'll be waiting to see how yours goes it will be nice if it works good I'm a big fan of the larger stepper drivers it is just to my knowledge other than bench test nobody's had good luck on a actual printer. And yes you can think of that way but the pulse for step and direction that they operate on is very fast compared to standard stepper drivers The older half step/full step

by Jim Fong - General

Re: Nema 17 - stronger motor alternative - 11 years ago

Quotecnc dick You said that there has to be many people that use external stepper drivers for 3-D printers I haven't found any if I remember right lobo CNC did on have their first 3-D printer and they have done away with it. If you find any case post a link or pictures video any thing. Anybody that is using external drivers seem to be running Mach 3 for their printer the majority are using inexp

by Jim Fong - General

Re: Nema 17 - stronger motor alternative - 11 years ago

Quotethejollygrimreaper I once had an issue with the tb6560 drivers which resulted in a modification to the marlin firmware which allowed the pulse output to be make longer by adding in a very short delay, i have re added the mod to my fork of marlin which also has a few other usefull goodies like hardware pwm capability and certain Mcodes are switched over to buffered https://github.com/jgrjgr

by Jim Fong - General

Re: Nema 17 - stronger motor alternative - 11 years ago

Quotecnc dick With Mach 3 of course every thing works fine that's what it was designed for but you said from the ramps the pulse for step and direction signal is to fast on the ramps this can be changed but I haven't seen anybody have good luck with it. I'm waiting to see how it goes there are ways to change the pulse by putting in delays in it will be interesting to see how it goes like I say to

by Jim Fong - General

Re: Nema 17 - stronger motor alternative - 11 years ago

I don't have my 3d printer running yet, just bench testing the drivers out with the ramps board. I have 4 CNC's running external drivers with MACH3. One of them is spinning the axis at 300ipm or about 1500rpm. That's limitation of the computer. Not fast enough to run the drivers at a higher speed. With a external pulse generator they will spin upwards of 2000rpm or more. All I am saying that

by Jim Fong - General

Re: Nema 17 - stronger motor alternative - 11 years ago

I use external stepper drivers which can easily be interfaced to the RAMPs step and direction lines. I bought these geckodrives for cheap on eBay. They can handle steppers up to 7amps. High performance drives that can easily spin nema23 motors well over 2000rpm. Overkill but I've been using similar drives on my big cnc and they never miss a beat. Parker compumotor and certain ones from leadshine

by Jim Fong - General

Re: Servos instead of steppers? - 11 years ago

I use servo on three of my cnc mills. They run great, reliable, but so much more than a equivalent stepper motor system. I mostly use gecko drivers, they are about $140 each new. I keep a look out on eBay and have bought a few for about $50 each. There is also more wiring to hookup. The 3d printer I am building will be stepper since I don't think using servos are neccasary for this application.

by Jim Fong - General