[peteeng]

Hi Ard - Thanks for the info. I have done quite a bit of slewing work but on cranes with very large rings. INA is a good brand will look those up. Peter

[StrawberryBoi]

I don't know the depth of cut in terms of radial depth, but they are cutting at 24krpm and moving at around 100-150ipm which is the limit of the machine under control. It rapids at 400ipm, but the Mach4 controller is limited to 150ipm while the spindle is running in the particular setup.

I myself have only cut foam and aluminum at max ipm, which is well under the tool maker recs for the endmill. I've even cut with a 1/2" two flute on the foam at 150ipm and 16krpm under the recommended rates from the foam supplier.

[StrawberryBoi]

I should say they are using high efficiency milling settings

[peteeng]

Hi Strawb - Well the chipload is the important factor so could you find out? or radial cut.

https://www.kennametal.com/us/en/res...and-power.html anyone used this and validated it? Peter

[ardenum]

let me save you some trouble, for the C axis(the axis you rotate the spindle head about/perpendicular to the table) I came up with a slewing ring/harmonic reducer combo. The stiffest slewing ring at small sizes is cross roller type, INA makes these quite affordable(XU product group). For my application I'm planning using xu120179 INA slewing ring and CSG-32 harmonic reducer. they fit quite nice. Total package costs about $600 give or take.

Scratch that CSG-32, I didn't pay enough attention, I was seeing sub $200 prices, but that was just the front bearing, the full thing is +$600 itself. I'm changing it to a regular planetary reducer, one of these: PLX090/TD090

https://www.aliexpress.com/item/4001...45f96650tSHBAk

https://www.aliexpress.com/item/3303...6b844a87WrNLu3

[StrawberryBoi]

The mill supplier says 300 SFM and 0.006" IPT for the 1/8" 1 flute we're using in 416 stainless.

The guys at work are running more like 900 SFM, but the tool supplier says very low ADOC and deep RDOC and the guys at work are doing the inverse of that.

See the attached doc on HEM, but I'll ask about specific feeds and speeds.

[StrawberryBoi]

This is from a different calculator, FS app for Android. This is pretty close to what they seem to be doing on the router, though I'll bet the RDOC is a little less due to power limits.

[peteeng]

Hi Strawb - The HEM article is excellent. The power of the spindle will always limit the mills MRR. Milli is a hobby/Maker machine so hobbyists aren't so much concerned about max MRR. I'll stay the course with the 1.5kW or 2+kW HS spindle. I've been looking for a 12k rpm one vs a 24k one.... Peter

[peteeng]

Evening All - I have been wondering if a steel truss would work for the walls. I'd prefer to build parts here then in China. But the base is too big for most machinists around here. But the walls are doable. So I use 16mm top and bottom plates and 100x100x6 trusses. The stiffness is 18/22/70 which is close. I can go to 9mm wall and 120x120. I can see that the 16mm is distorting in between the braces. So an angle or channel at the top to fix that. The steel weighs 48kg and the granite weighs 75kg so well ahead there. Also have to run it with the CSA to check if casting is possible. Started going thru my 5 axis muses will get to that soon. Peter

[StrawberryBoi]

Jianken offers a 12krpm spindle at that power. It's among their 'constant power' spindles, ie that are designed for field weakening up to a higher speed. The JGH105-2.2 would be a 2.2kW, top speed is 21krpm, but peak power occurs at 12krpm, which puts it at around 1.75Nm continuous.

https://www.jian-ken.com/constant-po...ng-center.html

*EDIT* I'm ordering a spindle from them for a client to drive some test equipment, not for milling. They've been very responsive but anything other than 'quote this spindle' seems to be beyond the english language capacity of the sales team. They are definitely trying, they just aren't following.

The quote I got for a 4.4kW spindle, the JGH125-4.4 was <$700. With a Sunfar VFD and shipping to the USA it was only $1300.

[peteeng]

Hi Strawb - Looks good, will have to educate myself in the spindle area.... I've been tossing and turning about steel, welding heat treat & transport between all these things. Well away from what I wanted/imagined in the beginning. Then I had a thought about a company I used to have parts made by on the Gold Coast. They have two or three very big mills that can handle Millis base easily and they have been reasonable prices. They run lights out and make very large moulds for plastic bottles, crates and things like that. So they can make the large parts and Apex can make the small parts. Happy with that. Camtech can even anodise the parts... Rethinking envelope to 400x400x400mm.

https://www.camtecheng.com.au/

[peteeng]

Morning All & Sundry - I've had a glimpse of what I was trying to originally achieve with Milli-HR-No10. All the parts are less or near 50kg, The base is 2 pieces but the design is modular. The wall holds the base parts together in 350mm sections. so you can have as long as you want just use the required number of walls and bases. Sort of like the rigi mill. The parts are billet aluminium except the column which currently is steel. I'll get back to that once I tune a few things. The basic envelope is 400x400x400 , it has a front "porch" so you can do long things transverse. I added a rear bridge but will make the walls thicker at the base to be stiffer. It scores 10/11/53N/um but I can see how to improve that... I'd like to stay less then 100mm thick for parts as 100mm is a common plate size. Maybe Z is 350mm, makes big delta to the moment but will work with 400 for now. Model mass is 350kg which is getting into acceptable weight territory... Footprint is 700mm deep by 800mm wide but it will get a little wider with the wider walls... Feeling better now. Peter

I'll explain a little about my resistance to steel, welding and heat treat and finish machining. A "production" workflow has to guarantee an identical outcome every batch and part made. Welding is a variable, if the welder that does the great job leaves, the next batch maybe wrong. If the heat treat is wrong the batch is screwed, if the welder uses a different sequence the result is poor. Then there are transport and logistics costs with all of that workflow. Many years ago I started a welded aluminium bicycle factory (we built around 2000 frames per year) and went through all of those movies. I brought the heat treat in-house and that solved 90% of our issues. But even then we had stuff ups. Like to save time one of the frame builders stamped his frames HT before he heat treated them! We had 50 frames go out in T4 not T6! They were soft and being racing mountain bikes some of them bent... so its not easy when its a 3 ringed circus trying to get something done. By billeting I theoretically get the same result every time off of a high quality cnc mill. All the work happens in the one place and everything will be made to fit and function tolerances. Hope that explains some things. If things go well then I may cast the pre-billets but that has some fur attached as well

[peteeng]

Afternoon All - The effort about casting is not in vain. I shall build the next production router using the CSA or Tetrium. Since a router does not need the stiffness of a mill its the way to go for those I feel... Peter

Here's one of my frames- was built in 1990 not 1984...
https://www.ebay.com.au/itm/Vintage-...p2047675.l2557

and another good to see they are still around 30 years on...

https://th.bing.com/th/id/R.84adf5f6...pid=ImgRaw&r=0

and the image is a bespoke aerodynamic frame made for Miles Stewart the week before he won the 1991 World triathlon on it. That was a good day for us...

[peteeng]

Hi all the image of Miles is during the race not the week before. Was hard to find any images of the frame or the race. Its a clip from a news video.. Peter

[StrawberryBoi]

Supplier quality management is a dedicated position in even fairly small companies for a reason, for sure.

I completely empathize with you struggles in getting consistent results. I also agree that unless it's a robotic welder, you will never truly have the same result even with the best human welder and the same one every time.

I've dealt with similar issues with CNC processes that were multi-vendor as well. Center less grinding, of all things! We had a lamination stack for a large servo motor that needed to be +/- 0.0005" per Y14.5-2009, so a profile tolerance on the diameter and not just the average dimension.

The grinder had the proper facility and equipment, but they didn't really take seriously that we could check this tolerance with our CMM in our Q/A department. They themselves could check it, but didn't because the machine was "dead nuts", per them. Theoretically, sure, but not when you don't keep on top of wheel wear, or chucking it with sufficient precision... particularly because this was a lamination stack and the OD and ID needed to be concentric to a tight requirement as well. The same vendor would first center less grind the OD and then ID grind on a different machine.

Wr were getting only 1 in 5 to spec and they refused to acknowledge the failure. Eventually we did a visit and made them show us the entire setup process. They didn't even dial the part in on the second setup!!!

Bingo, issue found. Thst supplier caused almost $60k in losses over just a few dozen parts, not to mention our customer in the semiconductor industry was delaying a multi-million dollar machine over a tens of thousands of dollars motor.

Even in house processes require constant vigilance and process development, so yeah, going a single machine process with a single vendor makes a LOT of sense.

[ardenum]

Supplier quality management is a dedicated position in even fairly small companies for a reason, for sure.

I completely empathize with you struggles in getting consistent results. I also agree that unless it's a robotic welder, you will never truly have the same result even with the best human welder and the same one every time.

I've dealt with similar issues with CNC processes that were multi-vendor as well. Center less grinding, of all things! We had a lamination stack for a large servo motor that needed to be +/- 0.0005" per Y14.5-2009, so a profile tolerance on the diameter and not just the average dimension.

The grinder had the proper facility and equipment, but they didn't really take seriously that we could check this tolerance with our CMM in our Q/A department. They themselves could check it, but didn't because the machine was "dead nuts", per them. Theoretically, sure, but not when you don't keep on top of wheel wear, or chucking it with sufficient precision... particularly because this was a lamination stack and the OD and ID needed to be concentric to a tight requirement as well. The same vendor would first center less grind the OD and then ID grind on a different machine.

Wr were getting only 1 in 5 to spec and they refused to acknowledge the failure. Eventually we did a visit and made them show us the entire setup process. They didn't even dial the part in on the second setup!!!

Bingo, issue found. Thst supplier caused almost $60k in losses over just a few dozen parts, not to mention our customer in the semiconductor industry was delaying a multi-million dollar machine over a tens of thousands of dollars motor.

Even in house processes require constant vigilance and process development, so yeah, going a single machine process with a single vendor makes a LOT of sense.

What do you mean refused to acknowledge the failure? I mean the evidence is there on the part? Sounds like an easy win in court. How did it end?

[StrawberryBoi]

Heh, specific resolution wasn't my department. I think we ate the material cost but they refunded their op costs.

[peteeng]

Morning all - I have ben trying to build isogrids, diagrids and hex grids parametrically for some time. Getting holes, perimeters and grid all lined up is tough... They must script this sort of thing. I want this sort of thing for the machine base... Peter

[peteeng]

Morning all - I have been working on making a clamshell isogrid for the base. The base will bolt together in 4 pieces. I will also make the walls like this as well. If I use camtech I could make the base in 2 pieces. Will decide once I get it better detailed. No11 scored 11/17/78N/um and I can see how to fix X. Was mainly to check apples to apples against the prior base that it was not off by a long way. The column is currently steel but that may become clamshell aluminium as well. I think I'll drop the 5 axis idea, detail this out to costing stage and see where it lands... The 5 axis can wait until the next router project so I can cast the parts... Peter

[peteeng]

Morning all- this morning I decide to run a bolt model for the base to get a reality check on its stiffness. It scored 9/16/42N/um vs the "same" bonded model of 18/16/79N/um and this is where my 50% efficiency comes in. Y did very well and Z is fine. So get the bonded X up[ over 20 and it will be OK. Plus I have to play with the preload and maybe the bolt pattern. I'll use hollow dowels with thru bolts in the real parts. Although there is no sign of slippage in the model... I used 1000N for the static load . Peter