[Titaniumboy]

Hi TiBoy - I'm guessing the ratio, as in the video the belt is closed up in a casing. Unless its a gearbox but unlikely to be a gearbox. The quote max speed is 8000rpm so maybe its a 5000rpm servo and smaller ratio? They do steel with light cuts. The vids look good but there are machine aspects that are poor. Like they run the ballscrews directly to the motors with no thrust bearing, so motor life is at risk specially if shock loaded. They use a leadscrew for the Z for some reason as well. The machine assembly videos are quite good so you see how they are doing various bits of the machine. I suppose if its in a commercial environment and gets a few 1000 hrs on it the owners will know. It does have some vibration as in one vid you can clearly see the chatter in the finish then it gets cleared in the spring cut...

In regard to the pulley diameter you pick a small pulley that works then get a big pulley to suit. 3:1 is common on various things. So you must have a space problem

Thanks for your thoughts on the MR-1 and how it gets away with cutting steel. Doing super-slow baby cuts in steel isn’t really a problem for the home gamer if it means being able to make a part as versus not being able to make a part.

My mill uses 5M HTD pulleys and belt. The motor pulley is 63 teeth (94.7mm flange OD and 24.6mm inside flange width) and the spindle pulley is 38 teeth (64mm flange OD and 17.5mm inside flange width) with a 17mm wide HTD belt. The servo motor is 3000 rpm and 1.2kW.

I was told by Novakon that the spindle pulley couldn’t get any smaller because “the power of the servo motor is significant and to properly transfer the motor torque to the smaller pulley, the diameter and the number of teeth engaging the belt drive is a factor. There is not much room to enlarge the motor pulley and the size of the smaller spindle pulley can’t be reduced for practical reasons. To make the ratio any larger would also limit the maximum size that can be tapped due to loss of available torque delivered to the spindle”.

I would happily trade away some rigid tapping capability for increased rpm.

[peteeng]

Hi TiBoy - If you want to do the numbers here's the design manual. If the belt is strong enough (tooth strength) it usually comes down to fatigue and it will fail early. But you get lots of warning about that usually. Peter

[Mogilogi]

Been reading the MR-1 forum and they are moving away from concrete to epoxy granite. They say this is because the EG cures faster so the build is faster. They say the concrete and EG machines behave equally... But I also expect from watching some clients assembly videos & what they say is the concrete was hard to do, need something that flows better around the steel embedment's. Peter

Hi peter, yes i saw this at their forum, as you said before i'm planning to use Grout or a better concrete mix.

[Mogilogi]

seems to be back on line!! Peter

to build an oven the size you need is ambitious within itself. You need to SR the entire machine in one go, then you need someone with a big mill to finish machine it. We have a forge at out mens shed and its hard enough to get small things to red... Getting a machine up to red, do you have a small power station at home? Lots of research to do yet. Peter

Yea i'm too much ambitious, that is why i'm here trying to slow my self down and get more information from experienced individuals.

[Mogilogi]

Hi Mogi - I have looked a few of Langmuirs videos and the MR-1 seems to cut steel fine. I suggest you copy it and you'll be fine.

Yes that is my plan from the beginning, to copy it and do better at the parts that they skimmed on to keep the price low.

I found the spindle info and they use an AC servo with a 1:2.67 belt (my guess). The servo runs at 3000rpm and they step it up so it can run to 8000rpm. You can get servos that run 0-6000rpm so no belts needed.

I saw it before and thought about something similar.

They use a leadscrew for the Z which I find interesting, use a ballscrew. Make it a bit stiffer then the MR-1 and it will work out. And do a better job at cable management...Peter

Yea i'm going with 20mm ballscrew on all axis, Gantry will be 200mm square, Y rails they are using 25mm thick plate, i will be using about 40mm, the width of the x carriage will be 250mm, z carriage 200mm and spindle plate 200m to make the distance between the linear bearings more to give more stability and so on, still researching.

or save up and buy the LR-1 much simpler. I'm sure your going to pay $4500USD plus by the time you get it all together. If I built that basic machine here in OZ ($4500USD = $6700AUD) I would have no change from $6500AUD although the machine would be a little bigger...

I whish, but since i'm Living in Turkey, i can't buy it from them so i choose the building route, since they provided a full video on the install process, i'm gonna follow it even cut the installing helping plates that you can see in the videos.

[Mogilogi]

The vids look good but there are machine aspects that are poor. Like they run the ballscrews directly to the motors with no thrust bearing, so motor life is at risk specially if shock loaded. They use a leadscrew for the Z for some reason as well.

Hi peter, this one of the places i will be fixing, will be using BK BF blocks to support the ballscrew to take the force away of the motor, having ballscrew for the z axis.

3) the saddle is highly webbed across the cars so is very stiff. That's if the real saddle looks like the CAD saddles on their site. I just found a picture of the saddle and it looks like an aluminium casting. very solid.

It's cast iron saddle as they mention.

[Mogilogi]

Hi Mogi - By the way if you make a mill and its uses coolant you will never do timber or porous stuff again. The lub and swarf goes everywhere and its a pain to try to keep clean,. So from that point on its a mill... If I cut aluminium on the router it takes me a long time to clean up the swarf and I find it 5m away from the machine over tables on the floor etc etc...

https://youtu.be/3DIkpsMBcIc

Yes that is something to consider while designing the machine, how can i switch between them i'm still thinking about it.

[peteeng]

Hi Mogi and others - Heres some heavy milling. I do like big horizontals. Peter
https://youtu.be/2lmXspvzwBE

[ardenum2]

Hi Mogi and others - Heres some heavy milling. I do like big horizontals. Peter
https://youtu.be/2lmXspvzwBE

floor type centers are very cool

[ardenum2]

.
here's how a steel double column could look like:

https://www.youtube.com/watch?v=cH9zw4oCCw0

[Mogilogi]

Hello all, i have a question to ask



this is the y Rail that will be on both side of the machine, the Top one the ballbearing and ballscrew will be above the linear rail guide, and inside the Y Axis Carriage, so it's below the X Gantry as you can see in this picture how Langmui did it



On the other hand, the Bottom one i will move the ballscrew to be away from the linear rail, it will be on the outer side of the machine, so the ballnut will be connected to the Y Axis Carriage by a extended plate as you see in the picture

This design will allow me to have the Y Axis Carriage from almost 70mm to 80mm to be as low as possible almost flush with the Y linear rail about 20mm to 30mm and to have my Y plates width 80mm not 100mm and length 1200mm not 1350mm and that cutting in width and length, it will be replaced by thickness of 40mm not 30mm

So my question is, Dose it matter which way i go with, the force on the ball nut, and the way the Gantry will moved and stability.

[peteeng]

Hi Mogi - Having the ballscrew above the rail is a strategy to minimise the machine footprint. Unfortunately, this also places the ballscrew in a poor position for machine stiffness. It increases the distance from the bearings to the gantry and makes for a complex casting in the MR-1 case. Machine stiffness comes before the drive logic. I would place the screw to the side of the bearings, In fact I would not design the drive system until you sorted the structure then fit the drive to the structure. It does not matter where you push the structure as long as it is reasonable. The structure needs to be stable (bearings as far apart as possible with a square "kern" or footprint. With bushes and bearings with high friction it's important to place drive nuts at the friction centre (otherwise stick slip will occur), but because cars with balls have very little friction the friction centre concept does not exist.

This also allows easier assembly and maintenance. A good machine has major assemblies that stack up like a pyramid. No need to pull things apart to get to bolt heads and nuts and no need to upset drive assemblies to pull top level assemblies apart. Once drives are settled in you don't want to pull them apart to pull the gantry off for instance, sort your structure first... especially your Z assembly it's going to affect your machine footprint. Peter

[Mogilogi]

Hi Mogi - Having the ballscrew above the rail is a strategy to minimise the machine footprint. Unfortunately, this also places the ballscrew in a poor position for machine stiffness. It increases the distance from the bearings to the gantry and makes for a complex casting in the MR-1 case. Machine stiffness comes before the drive logic. I would place the screw to the side of the bearings

I'm happy it's like that I thought I will have to make a complex X carriage, for the footprint it dose not matter that much for me

In fact I would not design the drive system until you sorted the structure then fit the drive to the structure. It does not matter where you push the structure as long as it is reasonable. The structure needs to be stable (bearings as far apart as possible with a square "kern" or footprint. With bushes and bearings with high friction it's important to place drive nuts at the friction centre (otherwise stick slip will occur), but because cars with balls have very little friction the friction centre concept does not exist.

Yea I can't catch my brain of thinking about this stuff

sort your structure first... especially your Z assembly it's going to affect your machine footprint. Peter

yea I'm preparing the z axis now I should of start from it already, it should be stiff so what come after it don't be effected by it.

[Mogilogi]

Hello all, This is my Z axis so far, didn't do any simulation yet, all the plates thickness 20mm, just the bottom bearing support 25mm

Height of saddle 400mm, Width 200mm
Height of Spindle plate 300mm width 200mm

This design is built around 200mm Square Gantry Linear guide rail Top and Bottom so that is another 30mm height

Distance between Gantry bearings 256mm

[Mogilogi]

I feel like i'm doing the simulation wrong here
1000n causing a 4.5micron displacement, i had to remove the linear bearings and no spindle, the force on the z holding plate all of it.

[peteeng]

Hi Mogi - You had better have a meeting with your machinist and figure out how you are going to machine the lands for the gantry rails. As drawn its a two setup job and registering the first land to the second land is going to be tricky especially parallelism. If your going to bolt the cars to the SHS without machining I doubt they will work as the section will be crowned or hollow.

As drawn your saddle will need flanges as when the load pushes fwd or back the middle will bend as the top bearing pushes it in the middle.... Your tool plate (the spindle plate) will need flanges as well

I'd be thinking about part weights and a general philosophy of build. I usually write a small rules list for the build so I don't forget my objectives and limits. Each of my machines has tried to cover various technical and commercial aspects that a one of machine like yours does not need to worry about but its good to have a reference otherwise your thoughts change and then you will always be chasing change.

For instance your gantry is going to be heavy and your unlikely to be able to pick it up and maneuver it unless you use a crane or hoist. One of my rules is no part to be over 50kg prefer 40kg so I can manage it myself. If you have gear then thats OK. The aim at the moment is to get the big picture right and make consistent decisions so your machine is commensurate with your objectives and resources. So you don't paint yourself into a corner....

Although 20mm will do the job I'd look at 25mm bearings they will suit the scale of your machine better and don't cost much more. ... The structure and bearing arrangement is important to get right up front...Peter

[Mogilogi]

Hi Mogi - You had better have a meeting with your machinist and figure out how you are going to machine the lands for the gantry rails. As drawn its a two setup job and registering the first land to the second land is going to be tricky especially parallelism. If your going to bolt the cars to the SHS without machining I doubt they will work as the section will be crowned or hollow.

As drawn your saddle will need flanges as when the load pushes fwd or back the middle will bend as the top bearing pushes it in the middle.... Your tool plate (the spindle plate) will need flanges as well

I'd be thinking about part weights and a general philosophy of build. I usually write a small rules list for the build so I don't forget my objectives and limits. Each of my machines has tried to cover various technical and commercial aspects that a one of machine like yours does not need to worry about but its good to have a reference otherwise your thoughts change and then you will always be chasing change.

For instance your gantry is going to be heavy and your unlikely to be able to pick it up and maneuver it unless you use a crane or hoist. One of my rules is no part to be over 50kg prefer 40kg so I can manage it myself. If you have gear then thats OK. The aim at the moment is to get the big picture right and make consistent decisions so your machine is commensurate with your objectives and resources. So you don't paint yourself into a corner....

Although 20mm will do the job I'd look at 25mm bearings they will suit the scale of your machine better and don't cost much more. ... The structure and bearing arrangement is important to get right up front...Peter

Hi Peter, sure I will speak to the person machining the parts for me, the bottom bearing holder it will be a bolted part so it will make it somewhat easier to prepare

About flange I will add to saddle and the tool plate based on simulation as much as I can

About parts weight all individual parts will be lower than 40kg just one expection the gantry can be from 35kg to 125kg based on which configuration I go with wall thickness from 10mm to 20mm and square dimensions of 100mm to 200mm

Still researching the benefits of going all the way on the gantry vs the lowest end

I have family to help me carry stuff 2 man with me so it's fine from that part. I can rent hoist to use also if it's required.

[peteeng]

Hi Mogi - This is the arrangement you should be modelling. The force is at the tool, so use a dummy tool with infinite stiffness. Ive attached a guide to machine testing Peter

shooting at 20N/um the spindle plate and the Z plate will need flanges or be very thick. My Z axis is flanged and is equivalent to around 60mm thick steel.

[Mogilogi]

Hi Mogi - This is the arrangement you should be modelling. The force is at the tool, so use a dummy tool with infinite stiffness. Ive attached a guide to machine testing Peter

Hi Peter, Dummy tool attacked to the spindle ? also shall I make dummy spindle with infinite stiffness ? since the spindle will be a weak point also ?

[peteeng]

Hi Mogi - If you make the spindle infinite stiffness you will make the z axis local stiffness infinite as well. Make the spindle from aluminium and estimate its inside diameter. You can also push on the collet. Once you do this always use the same spindle and stiffness's etc so your apples to apples into the future. I'd moint the spindle to the z axis with some small standoffs so the z axis can move a little. If you "bond" the spindle entirely to the Z plate if will be over stiff. Can you model a friction contact? Peter