CNC Router Parts, 48x96 Questions

[Mike Konobeck]

I built the 50x50 KRMx02 by Kronos Robotics. There is a 50x102 "version" you can build. There is a kit of electronics and a few mechanical parts from CNC Router Parts that is outlined when you buy the book. Just has a different design using more 80/20 and is more stout. Not going to go into great depth as you can look them up but there is great support from the author of the book via the forum which you get access to once you purchase the book. Either way you will be fine. The components are easily replaced if they wear out/break and you can afford to keep spares on-hand if something breaks.

The router vs. spindle debate will ignite a lot of just that, debate. Lots of low production CNC routers use handheld routers. Many of which are the 2.25HP rated models. As mentioned, bearings are CHEAP ($5 for my Bosch routers) and you can change them out yourself. Just keep a spare router and you have a very redundant setup. You are talking about some serious runs though so I am sure there is benefit in you going with a spindle. Just remember that if something goes wrong with any spindle it is usually not a DIY job to repair and unless you can afford to be down for a few days and/or have a backup spindle on-hand then there are some personal choices you have to make in regards to what you want to do. Some day I may upgrade to a spindle. For now, with the Super PID and a router I have been really happy. Most of the time I don't need to run the router at top speed where people complain about the noise of a router. Running it at lower speeds, appropriate for the material and plunge/feed rate, extends the life of the router and tooling.

The Nema 34 vs 23 debate is another one that I don't understand. Mostly because of my limited technical understanding of the difference. You get better resolution out of the Nema 23 kit and it seems to me that the 34 is only good if you are doing some heavy cutting for long periods of time. Not sure if your question about using it 8x5 is really how you are going to use it or if you just wanted to get someone that has used the design enough to stress test it. If you were using a router by hand before then your throughput is going to go through the roof with a CNC router so you must either need the extra capacity because of growth or you plan on running it for those hours in batches and don't need it to perform at that level constantly.

Whatever works in your budget. You can always upgrade to a spindle if you decide a router is not right for your work or upgrade the electronics if you are pushing the 23 too much. You seem to be just getting started with a CNC router so you are going to have A LOT of other decisions to make along the way. The frame/design is important but all of the popular designs are great. Just pick one and get started. I thought about it way too long and no good came from over thinking it on this one.

[Ross Moshinsky]

The difference between NEMA34 and NEMA23 is power. CNC machines typically have 3 choke points: machine rigidity, spindle power, and drive power. Using a NEMA34 setup simply makes the drive power less of a limitation. If you're building a machine for production, upgrading to NEMA34 motors is probably wise.

[Mike Heidrick]

The difference between NEMA34 and NEMA23 is power. CNC machines typically have 3 choke points: machine rigidity, spindle power, and drive power. Using a NEMA34 setup simply makes the drive power less of a limitation. If you're building a machine for production, upgrading to NEMA34 motors is probably wise.

OK, Lets explore this advice a bit more.

This is what Ahren posts in his FAQ section:
Should I choose Nema 23 or Nema 34 motors to cut aluminum/oak/et While the motors that drive a system are important components, they are not the determining factors in what materials can be cut -- this is far more a function of the mechanical stiffness of the machine doing the cutting, as well as proper speeds, feeds and tooling for the material you wish to cut. Motors serve to accelerate and decelerate components of the machine (such as the gantry or z axis), as well as to push the cutting bit through material. As such, you may want larger motors in order to take deeper passes through material, to improve cutting times, or to drive larger format machines with heavier gantries or cutting tools.
The limiting factor for cutting different materials is typically chatter or machine deflection. These can be solved with machine mass, added bracing and structural components, proper cutting tools, shallower cutting depth, or most likely a combination of all of these. With a sufficiently rigid machine, either of our motor systems can cut aluminum or even steel.




I can rapid 1000ipm+ and cut at whatever speed I want with nema23s and a G540. I can easily out pace the bits desired speeds in wood and other materials. That's what I do not get when it comes to nema34 on his machine or a Joes? He pairs the selections of the G540, motors, and PS so well I have never had a cutting operation where I wished for a larger motor.

The rigidness of you machine, its base, and the fact that it is 8020 is really the limiting factors in these builds.

Also be aware, most will choose a G203 solution for steppers vs a G540 with a nema34 choice. Lots more money in the controller build, you need a break out board setup, the R&P kits are more, and the steppers are lots more. Do the math and understand what the costs are is my advice. Also research available power supplies for the G203 setup.

[Ross Moshinsky]

Mike, like I said, there are 3 choke points. If you have an MDF machine, NEMA34 motors won't make a difference. If you have a 1HP trim router, NEMA34 motors won't make a difference. If you use a CNCRouterParts kit with a strong welded steel base and a reasonably powerful spindle, NEMA34 motors can make a difference. Ahren will say the same thing. You won't see the impact on every job and every material but on some materials the NEMA34 motors will simply help you run the jobs faster.

It's up to you whether you want to spend an extra $1000 for NEMA34 motors just like it's up to you to buy a $500 spindle setup vs a $100 router. Personally I believe that if you're building a 4x8 router for a production environment, you should try to make it so you can compare well against an EZ Router or ShopBot machine.

They do carry the Nema 23 setup as well. I don't think you can get much better on the price considering they have the cables ready to hook up to the G540 drive.

I have run both sizes and will say they both work well. The Nema 23 setup works pretty good for slower and shallower cuts. The Nema 34 works faster and can cut deeper in materials. The Nema 23 setup ran 700 IPM rapids and the 34 I run at 2,000 IPM rapids.

In running 1/4" spiral bits in 1/2" material in a single pass the 23 I couldn't run and the 34 I can. So instead purely basing your decision on costs, factor in what you will be cutting, how fast you want to cut and so on.

Another pro for buying from CNCRouterParts will ship everything at one time and save on shipping and having to source more parts.

I still have the first batch of drive plates from Ahren. I have built 4 machines and 3 of them are still running. Machine 3 was built using parts from Machine 2. Machine 4 and 5 use the 34 parts and run 30-40 hours a week and I haven't had too many issues with any of them. And they give really good support after the sale.

Sean

[Mike Heidrick]

You are making generalizations and not stating how, anything specific in your settings of your software using these nema 34 motors will make anything faster. It is not a matter of arbitrary larger motors making things faster. You have to configure them to be capable to be faster. What settings make them faster?

Did you build your own CNC machine? If so what are you using for steppers, motors, linear motion technology, and post processor software?

[George Carlson]

The problem with the 7518 is not the bearings, it's the brushes. Quote from the 7518 manual:

"At approximately 100 hours of use, take or send your tool to your nearest Porter-Cable Factory Service
center or Porter-Cable Authorized Warranty Service Center to be thoroughly cleaned and inspected.
Have worn parts replaced and lubricated with fresh lubricant. Have new brushes installed, and test the
tool for performance."

The 100 hours of use is less than 1 month on a CNC machine. If the brushes go bad. the commutator will burn, and you might as well trash the router. The 3ph spindles are brushless. The bearings in my spindles are easier to swap out than a router because when the front cap is removed, the rotor with the bearings drops out, there are no brushes to retain or remove.

[Mike Heidrick]

How hard is to add and swap a Super PID to a router?

[Ed Harrall]

Don't run the router on high and the brushes last a very long time. I have run one for over 2 years on the same set of brushes since i started slowing down the router. It has not effected the quality of the cut, it maybe improved it some.

[Mike Konobeck]

The Super PID is relatively easy to install. If you had to swap out the router completely it might be a little bit of a pain because the sensor is hard wired to the router. You could easily just order a couple sets of the sensors (RPM and temp) and just install them on a second router so it is ready to go. Then it is just a matter or routing the wires back to the G540 or have a quick disconnect and you could be back up and running in a few minutes. Another option is to figure out a way to mount the sensor using a set screw or clip of some type so that you can simply pop the sensor out of one router and mount it to the next. Regardless, you will have to drill the hole, paint the spindle, and remove the variable speed module in the spare one(s). Again, not very hard at all once you have it down.

[Brian Martin Pennsylvania]

Thanks everyone for your input. So this is what I figure on getting: CRP 48 x 96 Nema 34, 2.2k spindle and fabricating my own strong steel base. Is the software easy to learn? I'm only cutting out strips out of HDPE that measure 18" x 3/4 and .250" thick and then I'm going to change tools and counter sinking 1/2 holes in the strips. I'm guessing that CNC Router Parts sends directions on how to assemble everything. I forget to mention I'm going to use a vacuum table as well.

[Mike Heidrick]

I'm guessing that CNC Router Parts sends directions on how to assemble everything. I forget to mention I'm going to use a vacuum table as well.

The 48X48 I assembled did not come with any documentation.

We watched videos on their site and on youtube by another builder.

I also built a vaccum table - I used a 3hp FPZ regenerative blower vacuum pump, a relieve valve by FPZ, a solberg filter, 4" vac gauge, and built a PVC/Ball valve manifold and routed that to zones under teh table. My system is 2" NPT/2" PVC.

One day I will pipe up this 4" 20hp roots blower vac. I got a thermwood plenum for it.