Відео

Great comment. Your concern is well-placed because that's exactly the problem I am dealing with now due to what are now some pretty obvious oversights on my part. Initially I selected magnets that were rated at 10 lbs of pull each. What I neglected to account for was that the hold down strength for each magnet nearly triples when you position them in between two steel plates, I guess due to how the field is influenced / focused. What I thought should have been 30 lbs of total preload force wound up being almost 75 lbs which made it an absolute bear to remove. It was also enough load to produce sufficient (enormous) contact stresses at the joint and it deformed the mating surface of the v-groove after repeated installations / removals due to the mismatch in material hardness (HRC60 ball bearings vs. HRC10 4140). As a proof of concept it worked pretty well (at least initially) but to fix this I think I am going to machine the baseplate out to accept some hardened inserts with the V-grooves machined into them that I can press in place. This allows me to experiment with different materials or replace them as needed due to wear without having to replace the whole baseplate and/or get it heat treated after machining. Right now I'm leaning towards hardened A2 tool steel for the inserts - on paper it should be close in hardness to the ball bearing but if you have any other suggestions I'm happy to hear them. They make carbide v-groove inserts for this purpose but I can't seem to find any in the size I need. I've also changed my magnet selection and machined the pockets for them deeper to cut the preload down to around 40 lbs which is very reasonable. I'm hoping between that and the material change the problem will be resolved. Also potted the magnets in epoxy to keep chips away from them. I'll be talking through these things in the next video once I work through this solution. Thanks for the comment

@@cskovach i ran into that exact problem in some kinematic optics stages I designed a while ago. I first considered using a heat treated high carbon steel / tool steel but it would be an uber pain in the @$$ to grind all the complex faces in after heat treat. (I’m pretty sure my machinist team thought I was insane for suggesting that option lol). I ended up using pairs of heat treated pins that were either epoxied in or press fit in depending on the design. McMaster sells HRC60 dowels from 1/64” to 3/4” with tolerances as tight at +1 to +3 tenths. Regarding the magnetic strength, depending on the material permeability and the arrangement of the magnet poles you can really some interesting field intensities. Best recommendation to avoid those issues as best you can without breaking out ansys to sim the field is to make sure all magnets have the same polar orientation eg all have north side down. Also remember magnetic attractive force is proportional to 1/(r^2) so if you had a 0.025” gap last time, doubling the gap to 0.50” will reduce the force to 1/4 the previous value.

@@andrewh2341 I have a concept worked up and I think it will be simple enough to machine, but we'll see how it works out once I get there. Obviously grinding them in would be best practice but I'm going to try it and see what kind of repeatability I can get out of it from just hard milling them. I made a clearance slot pass straight through the part to allow me to hit the chamfered edges with some precision ground flatstones to try and get rid of any high spots. Repeatability testing will reveal if any subsequent processing is necessary. Exact Engineering does pretty much exactly what you suggest with the dowels. It was an intentional choice of mine not to copy their design so I sought out other ways to obtain the same functional performance while trying to keep machining on the baseplate simpler. I have a 4th axis that I could use to do that but haven't had a whole lot of seat time on it yet. Thanks for the info.

Thanks Jesse. I'd probably still be chewing on the decision to pursue the cnc world at all if it weren't for your online academy to help make it accessible and I'd certainly still be chewing on this particular application if it weren't for your video, so thank you guys for the inspiration. It has changed my life. I'm not a design expert either - there's always room for improvement on anything (including this) but if you approach each situation with humility and a curious mind you never stop learning. At least that's what I try to do. It's hard to argue with the repeatability you were able to achieve with your design though!

Thanks Steve!

Good stuff Steve

In general ...the holder is not a problem....but the tool must have trough coolant for accuracy and high speed.... ! Rough and rest rough....there is the problem.

You’re probably right. Got some tools and materials coming and will be doing some more work on it.

You tend to learn the lessons hard and fast! I keep a running “lessons learned” document that I add to every time I machine something. Speeds, feeds, setup, mistakes, etc.

@@cskovach yessir. Got another interview as entry level material handler for a big company. Pulling stock and cutting it. Would be a great way to enventually make it to their machinist positions. $. Been out of work since November at my last machinist job. Dropped the price of my parts I sell online to the lowest I’ll go. Times are rough. Wish me luck.

@@durangotang1681 its funny. Some guys seem to be busier than they’ve ever been and others can’t find work to save their life. It’s tough sledding out there for sure. Best of luck man

@@cskovach well, they sent me their “eat shit” email today. Fuck em. Moving on lol.

@@durangotang1681 on to the next one man. Keep it moving

I’ve experienced the same thing on the PM forums. If I had listened to their advice as someone interested enough in the trade to consider buying their first machine, I probably wouldn’t have done it because if you don’t have 6 figures worth of machines, 80 years of experience and a dozen or more customers beating down your doors for parts you’ll never make it according to them. But ya gotta start somewhere and they certainly did too. The key is in having enough courage to give yourself a chance to figure it out and to see what happens. The learning curve is brutal but once you understand the basic principles you will struggle a lot less (at least that’s what I’m telling myself!). If you develop a good process, you will make a lot less mistakes and over time become a lot more efficient. Glad you found the video useful. If there’s anything else in particular you’d like to see let me know

It’s an interesting thought. Tool deflection would be pretty severe though since you’ve got probably less than half of the total tool cross section as the 1/2” em 2XD deep on a 1/4” cutter with .010” per tooth and 30% stepover at what would be borderline steel SFMs sounds like a great recipe for breaking tools, but maybe 3/8” would do it

I’m really curious to try something like a KOR5 or a similar tool from helical. If I were to run it at 8k where I have a little more torque maybe I’d be able to access more of the available spindle power. It seems ridiculous to have 75% headroom on a cut like this, based on spindle loads anyway. Curious to see how much more I can get out of it.

@@cskovach We typically run the KOR5 in our Haas VF2SS at 12k RPM, 1mm WOC, 80mm depth, 0.15mm FPT. It's about 100% spindle load. (the KOR is in a 32mm Hydroforce chuck)

@@dutchr4zor what diameter tool? 80mm is deep. Since the video the max I’ve worked up to on an actual part was with a 1/2” helical hvalc5 5 flute chip breaker. 8000 rpm at 1.25” deep, .075” stepover and 300 IPM. If I recall correctly it read around 35% load on my machine but it’s more torque limited than hp limited up top.

Yes that was the whole point of the video

put spec for max cut feed

Thanks for the suggestion, I’ll have to check it out

That is a Titan USA 1/2" 4 flute end mill. www.titancuttingtools.com/products/tool-details-tc99533

Hey Paul. I'm using a combination of things - for initial recipes I'm using Machining advisor pro from helical tools. You have to make an account but it's otherwise completely free to use. For on the fly changes, I check stuff with the "Journeyman machinist" app on my phone.

Downloading now! I’ll give that a try. Thanks! It helps to have a good foundation to start with.

That is true. But the simplification works because in this application, torque (work) is not a function of time. The motor runs at a constant rpm during the cut and has a defined torque available at that rpm. If you had spindle rpm variation following say a sinusoidal pattern throughout the duration of the cut like what some machines do to prevent resonances from taking hold, then yes - integrate away. Thanks for the comment. Been a little while since I’ve dusted off calculus-based physics!

@@cskovachsure. I guess I was thinking more from the perspective of MRR being the goal. Then you’re thinking more about power than just the torque required per chip. I’d be interested to see what happens with this setup as you increased the feed or used a larger cutter. It might be a worthy experiment to throw a cheap end mill at.

@@benjaminpauza159 right, MRR is the goal. Torque is only part of the conversation because it seemed like I was reaching a point where I didn’t have enough, given the loss in rpm. Definitely need to do a lot more testing. I’m getting pretty close to the maximum feed which is 393 IPM on this machine, so from there tooling selection will be my only real knob to turn to maximize MRR.

Regular mpg mode functions that way. You can change the step resolution from .0001”, .001”, or .010”. I just tried it within that same program though and Mpg sim mode does not seem to respond to that, it moves the same step with each “click” of the wheel regardless of what you have the mpg resolution set on. Though you control the step size somewhat with the feed override. It could be how my program is written though. I need to investigate that.

I see. Thanks for the quick response. Do you think it works with other programs differently to make you think it has something to do the way you wrote the program? Please keep us posted on what you find out. Thank you. And subscribed! 👍

@@paulboon2285the reason I say that is you’ll notice I don’t define a feedrate for any of the axis motion in the program. It is operating based on the rapid feedrate override. I.e I start it down at 25% rapid, then ramp it up to 50% once 10 minutes or so have passed. I’m not an expert in g-code - barely have my feet under me in that aspect so I didn’t want to rule out the possibility of what you were asking about due to my own ignorance. If there’s anything else you want to see with the machine or the control let me know and I’ll try to demonstrate it to the best of my ability.

Thank you sir. I've got a lot to learn but I'm having a good time with it

I’ll give that a try. Looks like just a really basic loop counter which I didn’t even think about using. So then you would just vary the number of cycles for each spindle step to spend the desired amount of time at each speed. Makes sense. Thanks for taking the time to type all of that up, really appreciate it.

Happy to help

Yes sir .075". The control has been great. I've never run a machine before and was able to figure it out with a few hours of seat time. One major pro is that all the parameters are unlocked on it - so if you need to change a setting during repairs or maintenance it's all available to you. The only real hangup with it at this point is that it doesn't have factory supported probing screens but there is a gentleman working on that as a passion project. Maducerules on youtube. As far as I know, Siemens uses all Siemens servos and Syntec uses all Syntec stuff. Both offer 3 year warranties on the control, drives, and motors. Not sure if there's a power difference or not, they phased out the 808 Siemens control in favor of the 828.

@@cskovach yeah when I was looking at quotes the Siemens model was substantially more.

I’ll do my best! If there’s anything in particular you’d like to see let me know.

@@cskovach stainless. 4140. Whatever you wanna do. Hard to find videos of anyone running a proven program in something other than aluminum with these. I work in 17-4 mostly. But I’m down for whatever you upload.

@@durangotang1681so far I’ve cut 1018, 316L, a little bit of 304 and some aluminum. I’ll try to put together some clips I have and get some material to do some more demos. In 316 I’ve done 220 SFM at .800” DOC with .025” stepover, around 50 IPM with a 5 flute bullnose which turned out to be a pretty conservative recipe. Didn’t push it too hard because I was trying not to scrap parts lol

@@cskovach that’s good to hear.