Spent the morning searching the site for some more information. Sadly I am not sure if I am just missing the right keywords in my searches or what..so I just decided to post.
Here is what I have right now...I have a grizzly X3, and have my order in for 3 G203V geckos on there way and should arrive in a couple of weeks. The laptop is already set up in its plexi enclosure, and this is where it ends as far as the CNC conversion goes right now, hence the post.
The X3 will be my second cnc mill that I have owned. I previously had an X1 with xylotex and 3 180 oz/in somthin or other steppers..cant remember the brand off hand. However there is no comparison between the two. For the work I do with my machines the X3 was the way to go.
Next question is the motors, chances are at this time I will be leaving the stock screws in place and not be doing a ball screw conversion at this time...I know I know, this can make a huge difference on the overall operation. But at this time the budget does not allow this, and once the mill is operational and making money then I can consider it.
Stepper motors, this is a little confusing for me, so let me give you an idea of what I plan for the mill. I will be machining 6061 AL, in small production for some after market parts. Thickness around 3/8" and 12"x8" size parts. Speed is important, so I this is where I am having some questions. what spec should I be looking at, I have not purchased my powersupply yet, once I figure what steppers I should get I will go from there.
So pacsci are a decent brand name correct? so the questions surrounding the steppers is which specs are most important and how do I use them to figure out which power supply to get. If you have specific links to motors and matching power supplies I would be much appreciative of that.
I would rather have motors that are a little more than what I need, coupled with a powersupply that is a little larger as well, than to undershoot and have to upgrade later.
If any of you have your X3 cnc'd and are using it in some sort of production I would be happy to hear what you are using and some insight as to what I should be looking at.
My overall objective is to cnc this once and get everything needed for a beefy machine and the only other upgrade later down the road will be ball screws.
I look forward to your recommendations/advice and info!
It may end up being cheaper to replace the stock leadscrews with ballscrews. My 280ozin motors were only 40 bucks a piece, and provide more than enough torque to drive this table. I cannot push against the table hard enough to stop the axis from moving when my stepper drives my X. Smaller motors = lower cost
Smaller motors = under 3 amp drivers = lower cost.
If speed is important, ballscrews are essential.
Also, it is easier to do something like install ballscrews from the get go and go back and install it. Because then you will have make a bunch of modifications. Use the mill in manual form to make all you need.
Pacific scientific makes great products. But in actuality, many other brands do. Kelling sells 280oz motors online for something like 39 bucks a piece, that's pretty good. HomeshopCNC.com sells a nice motor as well for about the same price.
Dig through mpja.com, they often have some nice deals on power supplies or at least parts of it to make your own. I got a 28v 14amp power supply from them for something like 35 bucks last year. It is fully enclosed, includes a fan, it is professional. Plus it has a 14v output as well, useful for powering the logics of electronics.
You need to define speed in terms of target rapid and cutting speeds. Normally, the rapid speed will be the driver for motor sizing.
Once you have the speed you need, you can use one of the free motor sizing programs to get a good estimate of the motor size needed for your application.
The stock lead screws are 12 TPI and will be about 35% efficient. The samesize ballscrew is 5 TPI and 90-95% efficient. The same size motor would be able to move the table at 2.4x speed with the lower frictional losses.
The rolled 5/8"-0.2 ballscrew nuts are about $25 each, so the upgrade is not as expensive as it would seem (unless you want ground screws)
Yes ground ball screws later. I know there is a huge need for it but at this time it is probably not going to happen. There are lots of other factors I have to consider, which would probably take me forever to explain it all here. So you will have to take my word for it that I know what I am doing...lol...just dont tell my wife I said that out loud
The plan is at the end of the day to have all the parts I need to have a very strong cnc, with very nice components, which will happen over time. I would rather not at this time purchase less powerful motors or powers supplies etc in order to get ball screws. Some of my rationale may not make sense, but the market I make parts for is something I understand and my business plans allows for some and not for others. I would rather spend the money on the motors and powersupplies now, basically the most I can afford then do another conversion later (ie ball screws, and spindle motor mod/replacement as well as a few other items of interest). That way I will only have to do one more conversion with the ball screws instead of motors and power supply later if I were to find out what I purchased was not sufficient.
Part of the issue is the products need to get to market sooner than later, manual machining is already in place on it but needs to go away so time can be spent on the manual lathes I have in the shop.
Currently I thinking of going through www.Campbelldesigns.com and looking at their machine tool motors 640/oz in, along with a power supply and possibly a break out board (if needed). Any thoughts on a set up like this?
I mentioned before speed is important, however I realize the efficiency will increase as the other parts are added later, Ie; ball screws, spindle motor. I need to take baby steps with some it though as I can not get everything at once. Selling off what I have and replacing it, is not a possiblity as the machine is making money and selling and waiting for something different or new is not an option.
The speed to market is the most important, and doing production work with the mill as a CNC runs equal to that. We already have 3 lathes going all manual and not able to focus the same time needed on the mill.
I probably missed some more info needed..but I think i have typed long enough for everyone..lol. but some more feedback back would be much appreciated.
You don't need to buy ground ballscrews. I suggest getting the 5/8-5 rolled variety. It is still well within the accuracy appropriate for this mill, and is inexpensive compared to buying unnecessarily large motors and power supplies for the machine to retain the stock leadscrews. You are going to have problem with backlash as well. Speed won't be so nice when you are not accurate.
HomeshopCNC sells ballnuts for 25 a piece, figure you need 6 if you want to do a preload. Then 1.25 per inch after that. 72" of screw overall will be plenty.
It's not that you will have to buy lower power motors and power supplies in order to have ballscrews. It's more that you will be able to save money by buying lower power motors and power supplies because of the dramatic increase in efficiencies ballscrews allow. Even when you adjust the backlash out of your stock leadscrews, the nut will wear and backlash will reoccur in a short while, especially if speed is a concern. You will have to be adjusting frequently.
I can vouch for the issues with anti-backlash nuts on acme screw CNC mills. It bit me pretty badly last week. I was having problems, and went to check and found .012" of backlash where there was .002" two months ago.
There are ways to calculate it to be sure, but as you increase the stepper size you run into larger issues with mid band resonance.
I think with ballscrews you could use 250 oz in steppers just fine. Indeed, that is what the Syil X3 uses.
I totally understand wanting to upgrade in stages, but if you make your motor mounts compatible with both NEMA23 and NEMA34, swapping out later will take you less than an hour.
well been a while but just an update. I ended up going through Ken at www.kdntool.com which is now the second time I have bought cnc stuff from him and as always he gets top marks for his service and quality. I have no problem recommending him to anyone looking for a conversion for your mill.
I did go with the vampire drives, and ball screws (not ground), 25o oz in motors (479 oz in or something like that for the Z) and mach3. I am very happy with the set up and very happy with the smoothness of the ball screws and the speed of the motors. This weekend I am going to play with setting up a joystick as I have a couple of the old playstation table top arcade style controllers laying around. My only regret is that I did not do a 4th axis...money was getting tight so the 3 axis will have to do for now.
The conversion on the mill itself wasnt bad to do at all. Minus moving around everything which is very heavy the only interesting part was having to cut out the back of the base to fit the motor mount and motor for the Z. Other than that it went together like a dream and now I have a few lead screws with handles and half nuts to use elsewhere in the shop. I have already started to build an english wheel with one of them
also wanted to throw in there...is there anyone in the austin tx area that has the same interest? looking to meet up with others with the same interest. I did post in the mentor section but also wanted to throw something in here incase that isnt a popular area for people to look
I talked with Ken about getting his conversion. I don't have time to design, manufacture, install, etc, just to get to make chips. I'm in manual mode now and my scrape to chip factor is equal. LOL
The one cost factor that you didn't mention was Frustration and scrapped parts from the ACME screws. As the frustration issues is not quantifiable but the scrap is, you probably saved money be getting the Ball Screws initially.
dont mind some of the mess...
was in the middle of a few things when i saw your post for some pics...I dont have the enclosure for the laptop up although I did bend some plexi to make one, and after all is said and done I will have put an enclosure around the table for chips and coolant ect...put in a pic of the joystick I am hoping to use. Just got the adapter for it today, so tomorrow I will test it all out and see how/if it works...