[digitalmdj]

Here is a pictures of my lathe so far. I thought I should start a post. You can see it as it develops.

[digitalmdj]

Here are some pictures of my lathe feed gearbox. You can see I replaced the steel bushings with bearing bronze bushings. It is very smothe after alot of deburing of the gears and modified lockscrews. Also here is a picture of the Thomson ball screw I am going to use for my Z axis and I will still be able to use the power feed and hand feed unlike the Shoptask Z axis ball screw which is strictly for cnc and you are unable to use the hand or power feed. If you going to do somethig then do it right the first time. Nothing I hate more is something just slop together. The drive gear for the Lathe feed gearbox the hole is to big and will have to be repaired.

[svenakela]

Keep the pictures coming, it always fun to see someone rebuilding machines.
But please, stop the Shoptask negativism. I'm getting tired of all your ranting (I think everyone knows your opinion by now...).

[digitalmdj]

For those of you that are having problems with tight lead screws try changing the outer thrust bearing from a ball thrust to a needle thrust bearing. You can buy them from McMaster Carr and they are made in Germany. The inside ball thrust will keep the shaft center and the needle thrust bearing will maintain better thrust and prevent binding caused by the two ball thrust working against each other from a possible slight misalignment between the two. I also ordered some tool steel that is used for gib strips . My gib strips are .200 thousands. This leaves to much clearance between the strip and the table. So I ordered metal that is .250 thousands thick and is already ground flat. This should take up the large gap and give me better adjustment on my gibs. If anyone has any ideas for the shoptask feel free to say something.

[sharpshooter90]

When we did routine maintenance on our machine, I found that the thrust ball bearings had one race that was a nice slip fit on the screw and one race that was larger and very loose. At first I thought it was a maunfacturing defect until one of the techs in the machine shop explained it to me. The bearings are designed that way to allow the screw to turn freely in the support bearing or bushing. The race which fits looser on the shaft always goes against the fixed bracket. If they are put in wrong, then the tight fitting race will drag against the bracket and cause a lot of friction.

[LeeWay]

Nice looking lathe. Can you mention what model and brand it is?
I want to build one myself, but if I can get a decent frame like your's, it would require much less machining and head scratchin.
I will stay tuned to your progress as well.

[digitalmdj]

To get the inner race aligned on both sides with no misalignment is not easy. The needle bearing on one side take the hassel away and both together add thrust and axial support that two ball thrust don't. I cannot consider my machine to be a shoptask anymore. I am in the process of modifying everthing the way it should be. It is taking some time getting the tools and metal together to make the parts. But I will have all the tooling to make everthing again when I get through. The reason I don't have the lathe on the bench is because I am building a new one and I am using the legs off the old one. It was easier to build a new one than modify the old one. I have limited time to work on it so I will post pictures a often as I can. Also getting a machinest to do piece work is like pulling teeth. They all want to make the big money and they don't want your business after a few parts. Even if you pay them what they ask they want to make a run of parts so they can get rich quick. It is frustrating a best. Ihave a frieng doing some of the parts but you cant use your friends forever. Most people don't think it is necessary to do all this. But thats why they are driving a geo metro and I am driving a Jeep JK modified the way it should be. Never be satified with the term just OK. It has to be right and don't accept any thing less. Especially if you are paying cash for it.

[svenakela]

To get the inner race aligned on both sides with no misalignment is not easy. The needle bearing on one side take the hassel away and both together add thrust and axial support that two ball thrust don't. I cannot consider my machine to be a shoptask anymore. I am in the process of modifying everthing the way it should be. It is taking some time getting the tools and metal together to make the parts. But I will have all the tooling to make everthing again when I get through. The reason I don't have the lathe on the bench is because I am building a new one and I am using the legs off the old one. It was easier to build a new one than modify the old one. I have limited time to work on it so I will post pictures a often as I can. Also getting a machinest to do piece work is like pulling teeth. They all want to make the big money and they don't want your business after a few parts. Even if you pay them what they ask they want to make a run of parts so they can get rich quick. It is frustrating a best. Ihave a frieng doing some of the parts but you cant use your friends forever. Most people don't think it is necessary to do all this. But thats why they are driving a geo metro and I am driving a Jeep JK modified the way it should be. Never be satified with the term just OK. It has to be right and don't accept any thing less. Especially if you are paying cash for it.

But if there were two angular contact bearings, and you replaced one with a needle bearing, there is for sure less linear force capacity left in one direction. And even if there were two ordinary ball bearings they would take more "thrust" than a single one.

[digitalmdj]

I am using a ball thrust on thre inside of my mill gearbox hand feed and a needle thrust bearing on the outside. With two ball thrust the shaft kept binding up when I tried to take out the end play. With the needle bearing installed I could tighten up the lock nuts and remove the endplay without binding up the shaft. Now the gears spin smoothly and I was able to take out the backlass between the gears also. The needle thrust bearing has a greater surface area and can handle more load . You can find load specs on the McMaster carr website if you have doubts. The shoptask bushings between the thrust bearings were replaced with bronze bushings and are a better fit also.

[fastlanecafe]

[[I] Also getting a machinest to do piece work is like pulling teeth. They all want to make the big money and they don't want your business after a few parts. Even if you pay them what they ask they want to make a run of parts so they can get rich quick. It is frustrating a best. Ihave a frieng doing some of the parts but you cant use your friends forever.[QUOTE][/QUOTE

If a person wanted to get rich quick, a machine shop is probably the last business he would choose. Running a machine shop is one of the most labor, equipment and accounting intensive businesses around. In order to be competitive, even a small-medium sized job shop must invest hundreds of thousands of dollars in equipment and hire very skilled people. A shop with an owner/operator and 1 or 2 machinists and a secretary/accountant will probably have a fixed overhead of $200.00 per hour. The business is so competitive and margins so slim that one error in estimating a job, or operator foul up can mean labor and materials lost for nothing. If a guy walks in off the street with a small one-off project, by the time the owner stops what he is doing while the customer explains what he wants- maybe accompanied by a drawing on the back of an envelope- and the secretary writes up a work order etc., the machine shop probably has 10 minutes of time invested in the job not counting the time it takes to do the work. Maybe the job takes 10 minutes to do, so the machine shop charges 1/3 of an hour- 75.00 for the work. Because its an odd job, they fit it in between their regular jobs and maybe it takes a week before its done. When the customer comes in to pick up his part and gets a bill for 75.00 he goes ballistic- he's already mad that he waited a week and now he is paying 75.00 for a job he knows he could have done in 5 minutes if he had his own lathe. He begins figuring that the shop made 75.00 for 5 minutes work which adds up to 900.00 per hour!! He imagines that this guy is bringing home 900.00 for every hour he spends at his shop and voila- get rich quick! In reality, the shop owner, after paying salaries, taxes, overhead, equipment payments, employee benefits and a million other things related to running a business, probably put 2.00 of that 75.00 in his pocket.
That is why shop owners don't like small one-off jobs and why folks like you and me and others on these forums invest in home machine shops. I was once the frustrated customer paying through the nose for small jobs and waiting weeks to get them back, before I bought a used shoptask. Now I do my own stuff when I need it or when I feel like it not paying, waiting or going hat in hand to borrow a friend's machine. Funny, though, I now find myself on the other side of the counter- It's amazing how fast the word spreads when you have a lathe and mill at home. Before long you have a steady stream of relatives, friends, friends of friends and neighbors of friends of friends showing up at your door with all kinds of projects that "will only take 5 minutes" and of course should be free. It's really hard to tell people that you expect to get paid for your work- they often look at you like " Gee what a jerk- if I had a machine I would help you!" Of course they don't have a machine because they don't want to spend money on one if you do the stuff for free. Lately I have taken to spreading the word about how much money I am making with my machine. Whenever the subject comes up I say " I made 50.00 per hour on my last job and the customer was so happy he is sending more my way" That gives me an excuse to tell my buddies that I don't have time to do their jobs because I am in the middle of a big project and have a deadline to get it done. Actually its not always BS, on quite a few occassions I have done little jobs for people that were quick and simple and the guy will happily slip a 20.00 in my hand and the shop I used to go to sent me a few jobs he didn't want and I actually charged the 50.00 per hour rate.
Sorry for the long post- bottom line is don't get discouraged- once you get your machine project done you will be pretty independent and can even do some paying jobs if you want.

[digitalmdj]

I am always willing to pay shop rates . But they feel guilty charging me. I don't complain because I know it costs alot to run a shop. They just give the impression they are to busy to do anymore for me. And then the next week they are at the business I work for begging for work. It doesn't add up . All they have been getting from us is small jobs and I can see it is effecting our relationship with them. They stoped coming as often and I had to call them the other day just to get them to show up to make some parts that we needed. They need the big jobs to stay in business. but if piece work is all their is then you do it to survive . The economy is bad right now and everyone is cutting back on everthing. The rule is you do every job that comes along because word of mouth is the best advertisement you can get. If you pick and choose jobs that what everyone will be saying about you and you lose work to the shop who will do even the rotten jobs without complaint.

[fastlanecafe]

That old saying about every cloud having a silver lining is mostly true. It sounds to me like you are in a perfect position to pick up a lot of steady work from your own company if this machine shop is dropping the ball.

[digitalmdj]

Here Is a Picture of my mill gearbox and Ball Nut with the adapter. I made the print and a friend machined the adapter for me. I will work perfectly and still allow me to use the power feed and hand feed if I desire. Unlike the cheap version shoptask makes that doesn't allow you to use the power or hand feed. We still have the ball screw to machine but thats another day. Iam working on the new gib strips . Ihave a teflon/moly coating I am going to try to see if it will work well enough to use.

[smallblock]

The older Shoptask machines required disconnecting the ball screw in order to use the power feeds, but my Patriot has manual, power and CNC drives functional at all times. I had considered going to ball screws, but the standard acme is pretty accurate at 0.0015" backlash. I would have had to use a really expensive ground ball screw to get any tighter. Keep us posted on that teflon coated gib strip idea if it reduces table friction.

[digitalmdj]

I am converting my machine to ball screws preparing to go CNC when I work out all the bugs. It will save time and money to do it now. The machine has to still be usable in manual mode also.

[digitalmdj]

I have started working on my lathe again fitting the new gib strips. It seem the old ones were to thin and allowed the gib strips to shift position. The new ones just barely fit between the ways. That way they cannot move and very little adjustment is needed. The table moves much smoother now. The teflon coating didn't work out very well but it did help to make the strips tight between the ways for as long as it will last. We will see what happens over time.

[digitalmdj]

I am starting on the X and Y axis ball screws. Does anyone have any ideas on who to contact for the ball nuts and screws. Please do not even mention Shoptask they are sub standard ball screws and I want a better quality setup. I would perfer adjustable backlass ball nuts.

[sharpshooter90]

We had the Shoptask equipped with servo CNC and ball screws in my outfit. Shoptask uses the Nook Industries select fit assemblies which claim a 0.004" per foot accuracy, which is a good choice for a machine in this price range. These will cost you about 50.00 per nut and 12.50 per foot for the screw material. Nook will machine the ends for about 150-200.00 per screw to your drawing if it's not too complex. They also offer a double pre-load nut for about 175.00, but due to its length, you may lose some travel on your carriages. The Thomson set you bought is about the same grade as the Nook. You can step up to a precision ground screw for about 50.00 per foot and precision nuts at about 250.00 each, which are rated at 0.0005" per foot accuracy, but thats a bit of an overkill on one of these machines. We had good results with the Nook stuff and the backlash compensation setup in the Mach II software.

[digitalmdj]

If your going to spend a lot of money on ball screws you might as well do it right and a little over kill might be the way to go. I like many other people always wish I had gone ahead and paid the price now and saved myself alot of extra money later to get what I wanted in the first place.

[sharpshooter90]

With some diligent hand work on the carriages and ways and a set of ground ball screws you can probably get the motions to any degree of accuracy you want. I would watch E-Bay and this forum for some good deals on ball screws. I have seen some on E-Bay pretty cheap as long as you can cut them and machine the ends to fit the machine. Once you get that part done, you will need to think about improving your spindles to match the accuracy of the carriages. Expensive machines like Mazaks have air cooled 10,000 RPM spindles that cost about 6000.00 each.