Wow, thanks for pointing that out! I just looked at the Lathemaster website and it looks like the X axis is about the same, the Y is an inch more and the machine is 200 bucks less! Yeah the head does look like a IH head! Are any other parts the same? I'm wondering if it's possible to bolt the 12"Y by 30"X table to this machine later? I wonder if Harbor freight can order one of these for me or if they will only sell sieg and grizzly?Quote:
Originally Posted by LUCKY13
I do believe the Lathemaster mill is a great value and a wonderful machine to cnc altho I must add that the head, while it looks like an IH head is not the same. My machine is a very early model and it has the larger ring on the column that is basically the same as the IH model at 12". The newer machines Bob is importing are the same type of head as the grizzly or rong fu models which have the smaller Z axis slide and the bolts tighten into some slots in the side of the head. The IH and my machine( and I am sure some other early ones that bob imported have the larger ring and three large bolts that go thru the flange and bolt on the Outside of the ring. If you look closely at the IH website and the Lathemaster website millhead pics you will see what I am talking about. Not to say that it is not a great mill, just that it is not the same as the IH model. The reality is that the IH machine is in a class by itself in the benchtop area. Even my machine despite having the same millhead is a bit smaller and shallower in the base and does not have those wonderful 12" x 30+" travels. I sure wish it did but I will have to settle for 23" of X, 9" of Y and something like 20" of Z. The base on my machine is also greatly different in the ribbing underneath than the Lathemaster mill they are currently selling. My machine has some thick ribs that actually go from side to side underneath the leadscrew where the new machine is all above and there seems to be less of them....The current lathemaster mill is a bit smaller than that.
Bob Bertrand is a great guy to deal with and has taken care of me long after the sale. I would buy another machine from him in a new york minute if he had what I needed. If I was to buy another Bench type mill tho, I would save my pennies and get the IH. Anything more than that would have to be either a large knee mill or even a freestanding bedmill. Good luck....peace
Can anyone tell me how many extra inches you can get out of this base by taking a grinder to it? I want to build electric guitars. 23" x is plenty for the body but 9" Y isn't. if I can get just a little more Y I could live with that though. 23" is almost enough for the neck of a guitar. I was thinking if I put it in the work envelope diagonally I might have just enough. Is there anything wrong with doing this?
I'm looking at several grizzly's that all look like they have the same base and table but this one says it's 21 5/8" by 7 7/8" travel http://www.grizzly.com/catalog/2009/Main/535 and this one says it's 24" by 9" travel http://www.grizzly.com/catalog/2009/Main/534 is one of these bases actually 2 inches longer than the other?
It's not generally a good idea to cut wood on a metal working machine. Your guitar production would be much better served with a CNC router table--Like maybe a 4 x 4.
CR.
The reality is that despite the fact that it would be possible to machine a guitar body on one of these machines if you could get a reasonably large Y travel out of it, A nice cnc router would do it much faster and probably better due to the higher spindle speed of a router. The cutters for machining wood need to get some higher speeds and there are a ton of different videos on youtube of guys making guitar bodies and knecks on these cnc routers. It might also be cheaper to build one of these machines than to buy and retrofit a mill for this purpose. If you gotta do it on a milling machine then I would think it might be able to easily be done with a fixture plate that would allow you to do it on a half and half setup operation. You could buy a nice aluminum plate and key it for the table and then machine some standoffs and holddowns into it to accept the body. Then you might be able to program the machine to do as much of it as possible with the available travels. Then flip around indicating on a specific part of the fixture and then do the other half. I would imagine if you were careful you could get it done without much of a transition line and then you could just hand sand the transition to be smooth. I would also think that the plate would keep a lot of the chips off the leadscrew and ways. I do recommend that you keep a shopvac running and somehow hold it near the cutter during the process. I have machined the inletting on gunstock blanks this way with good success and an endmill cuts surprisingly well in wood despite the slowish speeds. Just keep it clean and go slow and you should be alright. If you were to get the IH mill, it has the largest Y travel which is something in the area of 12 inches and that would be the easiest for the whole operation altho more expensive machine.....peace
Thanks Pete, Thanks Crevice reamer. I've got to be able to cut metal too so I don't know about a cnc router. I was planning on maybe doing what the X2 Freak Guy does and temporarely bolt a router head to the original head to get those rpm's when I want to cut wood.
The machine is working fantastic so far. I have had several requests to post pictures of the retaining mechanism that prevents ball nuts from spinning relative to each other and here it is.
To make something simple - decided to design some 6-oz ingot molds from graphite. Below is the six cavity plate done in one setup - plate measures 6" x 6"; pockets are 2" x 1.25", drafted 4 degrees to the depth of 0.625". Machined using 3/16" 4-flute ball mill at 4,000RPM with 50ipm feed rate.
http://www.skyaerial.com/cnc/parts/DSCN1489.JPG
http://www.skyaerial.com/cnc/parts/DSCN1495.JPG
http://www.skyaerial.com/cnc/parts/DSCN1499.JPG
http://www.skyaerial.com/cnc/parts/f...x%20cavity.jpg
http://www.skyaerial.com/cnc/parts/DSCN1501.JPG
Very nice! You're going to try to pour your own aluminum ingots? How are you melting it?
I do not understand however your ballnut setup there. It seems to me that if you use a plate attatched to the ballnut return threaded holes and it is obviously a rigid setup then you have not really preloaded the ballnuts, they are just fixed relative to each other. The slight irregularities of the ballscrew do not have anywhere to go but to force the ballnuts apart. Maybe I am missing something but I was under the impression that to properly preload a ballnut assembly you need to have one ballnut fixed to the mount and then spring load the other ballnut either towards or away from the other ballnut yet still allow it to float against that spring pressure. The preload setup I am using allows the floating nut I will call it to do just that, it floats yet is not allowed to unscrew away from the fixed nut allowing for the preload spring pressure to give and take as the screw thread expands and contracts with heat and the subtle irregularities of the threadform. Am I missing something here? I suppose it is working for you tho from the looks of the parts you are making with it.... good work and peace...
as he stated earlier he uses belleville spring washers in-between the first nut and that collar. As he rotates that collar the preload increases. I had a similar idea to this that I will be using when I get to that point in my build.
That's all well and good, but I agree with Pete. Using the mounting holes from the return tube looks like it will constrain the motion of the nuts such that they aren't allowed to float back and forth lengthwise on the screws. If they can't do that, then they might as well be rigidly attached to each other and ditch the springs.Quote:
Originally Posted by Starleper1
A detailed picture would be worth a 1000 words here, as it's possible I'm missing something.
You see, if I LOOKED at the pictures it might be better. I reaffirm what I said, it constrains the system in a way that isn't the best. You want the second nut to float axially while being constrained radially. I used a dowel pin against the side (two actually, but it only technically requires one).
Yup, agree, the two nuts are held not only from rotating independently, but also from moving further apart independently to take up the residual backlash.
Still, that mechanism isn't far off. It just needs to be re-engineered slightly so the lefthand ballnut can slide relative to that bolt. Make a bolt with a raised shoulder, and put a slot onto the bracket and you are there. The bracket would look more like this:
http://www.cnccookbook.com/img/Lathe...lnutLink3D.jpg
If it were me, I would consider something a little beefier. One could also build a sliding link that is integral to the ballnut mount. Something more like this:
http://www.cnccookbook.com/img/Lathe...LinkModB3D.jpg
In this design, an outrigger from the ballnut mount (green) provides a sliding track for the rear ballnut (ballnuts are red). The Bellville preload assembly (gray) is threaded onto the rear ballnut and bears against the front ballnut.
Lots of other ways to go too.
Cheers,
BW
True, but the ball screw does not have the type of irregularities you are referring to at that short of a distance (maximum deviation is 0.003 over 12" of linear motion, not over 0.5" separating the two ball nuts). Consequently, you will never see any movement that can be measured with standard digital calipers - I didn't. Also, notice that the bracket profile is narrow, allowing the ball nuts to rotate against each other couple of degrees, which will address irregularities of 0.002" - probability of which at that distance is nonexistent. 100lb of preload will overcome any irregularities and induce the retaining bracket to accommodate thru flexing. The ultimate test will always be the sound of your system and the load on the stepper motors. This design, though may seem otherwise, is considered "floating", and the system performs incredibly smooth at high speeds without back lash.Quote:
Originally Posted by escott76
Even if the collar has spring washers in it, it threads onto the second nut and compresses the washers pushing the two nuts apart. The only way I can see that this would work is if you were to preload the nuts apart measuring the amount of spring deflection to get the necessary preload weight and then measured your hole distance and machined that fixing plate to hold the two at that distance. The thing is that even tho the two are technically preloaded, they are fixed and the only movement available is the backlash in the balls inside the nuts since the nuts cannot move independently of one another. Does that make sense? I have a friend here who has come up with a great idea for a preloaded ballnut setup that uses only one machined part. Country Bubba(don't let the name fool ya) designed a cool threaded collar that houses some spring wavy washers and is pinned to the mount by a shcs. Works real nice and is easy to adjust. If you look at the pictures on my thread" Finally getting started" you will see what I am talking about.... easy simple design and again uses only one custom part that is easily machined in the lathe. Another nice thing about this design is it placed the two ballnuts on either side of the mount to make for less travel restrictions either direction. Peace....
I'm with you A.S. If the MAX deviation is .003" over 12 inches, the most you'll ever have to deal with in .5" is .000125. That's 125 MILLIONTHS guys. That small piece of aluminum isn't going to be stiff enough to keep that from happening. Especially through a couple small fasteners! Also, as A.S. states, the nut can rotate somewhat since the aluminum strap isn't that great in torsion. That 125 millionths of an inch translates into 1/1600 of a turn - less than a quarter of a degree (which is less than .002" on the circumference of the nut). And this is all WORST CASE, it's likely to be about half that.Quote:
Originally Posted by asammons
The entire system isn't stiff enough to be the problem you are theorizing. Remember EVERYTHING is a spring, some are just stiffer than others.
so who do you guys like fore ball screws and nuts?it is tiring that the price seem to never be listed..... always call for quote . ...which always seem to translate into special screw you price.:)
I have used Roton 5/8" x 0.200" right hand ball screws (part number 59321, $10.09/foot) and Roton square ball nuts (PN 19193, $23.55/ea):Quote:
Originally Posted by the4thseal
http://roton.com/Mating_Components.aspx?family=7059321
I think you are confusing the leadscrew pitch accuracy specs for backlash specs. The purpose of 2 nuts is to minimize backlash and has nothing to do with the leadscrew pitch accuracy.Quote:
True, but the ball screw does not have the type of irregularities you are referring to at that short of a distance (maximum deviation is 0.003 over 12" of linear motion, not over 0.5" separating the two ball nuts).
One nut must be free to float axially ;).
Steve
In the above discussion, the pitch accuracy is what is used to determine the AMOUNT of float that will be necessary. The whole point is several posters were commenting that there was no float, but in actuality, the system isn't nearly stiff enough to prevent the float that is needed - therefore the problem that was theorized is non existent (which is consistent with A.S.' experience).Quote:
Originally Posted by S_J_H