mikenlapaz

Got a friend's Central Machine 7x10 lathe to use. After the second try on making an aluminum plug to press fit clearance, I noticed there is play in the cross travel part. The fit in the dovetail is good ( the 3 little set screw things) The play is ,I think on the screw with the handle on it.

It is not consistant. You can may a cutting pass, back up to right, engage feed and it may cut a greater amount than it did on the first pass.

Help...Ideas

tim220225

My Feedback: (4)

That sounds like a backlash issue. The 3 set screws in the dovetail area are the adjustments for the gib. On my Clausing the screw for the compound and cross slide ride in a brass "nut". Looks like a tee. Get the manual and see if there is a way to take up the slack and see if there is a nut or something else that can be replaced or adjusted. Being an import parts may be hard to get. www.littlemachineshop.com would be your best bet. Chris is the owner and will talk you through your issue and may have parts for you. Also make sure when cutting that you have the feed screw against the backlash. Meaning if you back the cross feed out to move the carriage back to take another cut, you need to make sure you are always turning the screw towards the part and stop at your cut point. If you go too far and need to back out a couple thou, back out beyond that point and move back in to make sure the cutting pressure is against the screw. Hope this makes sense.

Campgems

Usually slop in a cross feed screw isn't an issue. It is common to have a 1/4 turn or more, even in tool room lathes. If you are having trouble repeating a setting after backing the screw back out and screwing it back to the same setting, then I would expect to see the nut loose in cross feed. A lot of them are held in place with a single screw through the top of the cross slide. I don't know how the 7x10 is made, so I can't give better instructions.

Just reading your post over, when you say cross feed, are you refering to the travel from the tail stock to the head stock, or the hand wheel feed that is perpendicular to the bed? The cross feed it the later, IE what you set the depth of your cut with. Sorry if I am telling you something you already know.

Even backlash in the feed is common and should not cause a difference in depth of cut.

Maybe a little better explanation of what is going on and I can give a better idea of what you need to do.

Don

w8ye

My Feedback: (16)

I always followed this procedure and never had any problem. To try to get the slack out of the nut will cause as many problems as it solves.

tim220225

My Feedback: (4)

Mike, here is a link to the product manual from Harbor Freight. http://www.harborfreight.com/cpi/cta...m&ItemID=44859 They sell the model you have.

Tim

captinjohn

I think Mike has thw 7x10...the 44859 is a 8X12...the same as my Lathe. I do not think that back-lash is no big deal. I think it is something you got to get a feel for. Try using the zero wheel and set it when you feel where the actual travel begins. Hard to explain. Capt,n

mikenlapaz

Wow!
Makes sense. I was not doing that. I was finishing the cut and backing the 'linear' left-right feed without taking pressure off cutting surface. At the finish of the cut when I just started to back or reverse the cutter would back away from the cutting surface.



The hand wheel feed perpendicualr. For me this is just another time when I lack the knowledge to use the propoer terms. Does slow down communication.

The project is completed. third try and very small numerous pass at the end and cut it off with a hacksaw.

I will practice getting rid of the backlash before starting the cut. That could have been the problem! Pilot error, plane was function satisfactorly.

Now that I have your attention, any good site or words of wisdom on how I, a novice, might put a 10:1 inside taper in a prop hub. No cutter looks promising from tools on hand.?

captinjohn

I woner if you can find a taper reamer....seems possible? Capt,n

w8ye

My Feedback: (16)

Reamers in Morse taper and B&S taper are very common. Don't know about your needs?

raw191

My Feedback: (18)

I work in a tool and die shop and we have this problem with our lathes as well. They are cheap import. My boss sold our Clausing and bought a chinese lathe that's bigger, but junk. It won't hold tolerance. If your cross feed has a brass nut, chances are it's slotted. You can adjust the "slop" out of it by tightening the screw that butts up against the nut, thus "crushing" the brass nut, making the threads tighter. You can check to see if your cross slide is indead moving by placing an indicator on a magnetic base against the tool holder. Make sure the mag base is on the non sliding part of the slide. You'll see right away what the problem is. Dull cutters also can do that. Hope this helps.

Ross

tim220225

My Feedback: (4)

The best way I know to cut an internal taper is to set the compound slide over to the angle. I have a pretty accurate Clausing lathe but even on that machine the degree engravings are very close but... So I take the crank and chuck it in the lathe. I then take a dial indicator and set it up on my tool post so the stylus makes contact with the crank on the taper. I set the slide to some close angle of set over and move the carriage back and forth adjusting the compound slide until there is no movement in the dial as it moves along the taper. This is the most accurate way to copy a taper I know of. Most crank tapers I have done are about 8 degrees. At that point you are ready to bore the taper. You need a small but rigid bar. I set mine up so the crank handle faces the tail stock or about the 4:00 position. I usually cut on the back side of the lathe and run the chuck backwards. Take light cuts working in and out until you have a clean cut. I usually make a test hub and bore the area where the threads go a little over size. That allows me to put blue ink or chalk on the crank taper and put the bored test piece on the shaft. Turn it a little and remove it. You are shooting for the ink or chalk to be evenly rubbed. If not adjust the compound slightly and take another test cut. After a little practice you can hit it in a couple tries. Sounds complicated but it isn't. Many ways to do it so check the web or pick up a machining book for boring tapers. Just have fun and practice with it and you can make some pretty neat things.

Campgems

Mike, most of the small lathes I've seen have very easy to turn crossfeed screws. If the gibs are not dragging just a little, it is easy to loose your feel of taking up the backlash. If you can adjust the nut on the lead screw to be tighter, or if you can adjust the handwheel to screw to tighten up the screw its self just a bit, and if the gibs have just a bit of drag, you can hold position a lot better. I have a small taig for tiny work, and the cross feed is a real pain as it is loose enough that a little vibration or chatter will cause it to back off.

A good practice when using the lathe is to make your first cut by screwing out the tool and then screwing in to make just a light cut. Note the dial reading. Now make your cut and when you get to the end crank the apron back to the right without touching the cross feed. Now, set the depth of the next cut and repeat. Just remember, the numbers on the dial are the amount you are taking off the radius, so you will reduce diameter by twice that amount. If you need just a final 0.002 or so off, make your last cut without changing the cross feed. You will always take off just a slight amount more due to the spring of the machine. Last point, if your piece is getting warm, let it cool back to room temp for the final cut. You can easily loose a couple thousandths of size per inch of diameter because of thermal expansion.

Don't worry about not getting the names correct, some of the term are not intutive. I had an awful time when I was on my apprinticeship when I would go to the tool crib and ask for something. I ended up explaining what I wanted by describing how I was going to use it vs calling it by the right name. Some 45 years later, I still am calling some things by the wrong name.

On the taper, it is almost impossible to match a taper with a home machine shop. One way around this is to use the same compound ( the second cross feed, the one you can change the angle of) setting. You can set your male taper up in the lathe and then using a dial test indicator, adjust the compound angle so you get a very minimum movement or none on the dial as you scan the taper. Now lock down the compound really well. Take a very slight cleanup cut on the male taper. Now, setup for boring the female part and use just the compound for travel. Shoot for a thight fit as just a half thousandth of OD difference can make a big difference in where the taper seats. Very light cuts, to the tune of a thousandths at a time for the final fitting stage. Check the fit to the male taper after each pass. Remember that after a hand fit, that you will move some more when the prop is pulled down. Make sure that you allow for this.

Don

mikenlapaz

Is there enough basic machine here to do inside tapers? From your comments and hints I recognize the experience.

I got a shortage of tools.
1) No runout dial indicator for matching the male taper;
2) This machine only has three cranks. #1 to move the main carriage on the beds (turns when auto feed is engaged); #2 a cross feed adjust cut perpendicular to beds and #3 a fine tune feed in between head and tail stock. Took picture to clarify.
3) No self centering bit to start true bore hole.

Humm, I know where the might be borrowed...........

tim220225

My Feedback: (4)

Mike that machine has the same feeds and travels as my Clausing or any other engine lathe. Your cross feed is manual feed where the bigger machines usually have power cross feeds. Just a few more tools and you can do it, you need to make sure the machine is mounted on a firm surface and make sure it is level. Left to right and front to back. Shim as needed. Just take light cuts and take your time. Remember also that if you need to remove say 2 thousandths to finish and you set your dial to that amount your cut all the way around will actually be double. The small size of the machine should not be an issue. Rigidity usually is so smaller bites of the apple are needed to compensate. I saw a guy who made a running and beautiful reproduction of a Harley Knuckle Head engine at a show one time. All on very small Sherline machinery. Here is a picture of my machine. Just bigger but same basic set-up.

captinjohn

Tim220225: My son-in-law & I, bid on a Clausing Lathe. It was new in 1971 and not used much at all. It had at least a 36 inch bed, and extra chuck with it. Also live center ect. It went for just over $1600 Yup...our bid was 2nd highest!!!! Capt,n

captinjohn

miken: Get a cheap pait brush and keep the ways brushed off. It is very easy and prevents problems later. Seems like I read a 1 degree difference in taper on mating parts...make them lock together better? I would like to know for sure. Maybe somebody can tell us for certain. Best Regards Capt,n[:-]

tim220225

My Feedback: (4)

Yes I have been there. They are out there but timing is everything. Seems to me the best time to buy machinery like that off of Ebay is when the weather is warm. I paid less than $2000 for mine on a buy it now. Built in 1974 and went to a school then to a highway department. Very little use but it needed TLC. Runs and cuts great now. Tolerance for runout over 12 inch test bar is less than .0005. There are several machine tool dealers out there also to deal with.

rangerfredbob

My Feedback: (13)

over the summer I got me one of those old craftsman lathes (109 or something like that) in neglected shape but workable for $25, it needs a lot of work and a lathe chuck (just came with a 3/4" drill chuck, but it's a start) and clean it up a lot and tighten everything up... I scavanged a motor from an old iron (you old guys will remember those...) and found a step pulley for $1 at a garage sale... it even came with an assortment of gears but that's about it... I'll start working on it again here after a while...

Campgems

Ranger, if I remember right, the 109 has a 1/2" threaded nose. If this is the case, my suggestion is to clean it up and put it on Ebay and make youself a good profit and then apply that on a good lathe. The lack of hollow head stock will drive you nuts. Almost everything you want to do is going to be between centers. Absolutely impossible to face off anything over 2" long. This is experience talking. I worked on and tried to use one for a couple years before the frustration became to much. That one, I sold in a yard sale. A couple years back, I picked up an Atlas 6" (same as the craftsman) with the square headstock. I was just rounding that guy out with new chucks and the likes when I found a 10x24 Jet in the paper and jumped on it. I made enough profit from the Atlas on Ebay that I paid for the Jet and had a bit left over. I think I've found my final setup now. The Jet for serious work, and a Taig for the fine stuff. I might CNC the Taig now that I have a way to turn parts while I've got the lathe tore down. Darn airplanes keep me from getting all the modifications on my machines done though.

Don

rangerfredbob

My Feedback: (13)

yeah, I know, it's kinda small too, and not too versatile otherwise (the tool holder and dead center that is, not to mention the MT1 or whatever... ) but I figured for the price it'll be fun to tinker with and can do some basic stuff, but being me I'm always on the lookout for deals and know a good machine when I see it... could have gotten a 7x10 for cheap if I had money at the time (dumped all my money into my conversion plane at the time, and was literally the week I got my first job...), it was the lathe that my prop hub was made on...

being me, I'll probably keep it around the garage and pull it out every now and then even if I do get something else, or pass it along to someone else for cheap if they are really wanting one... or just make a quick few hundred bucks

mikenlapaz

captinjohn You are correct, the paint brush is nearby.

FWIW: I gave the machine a cleaning removed the cross feed, found where and how to rotate the feed, the cross feed is fine that screw runs thru a brass nut about 1.25" long and it is securely mount.. Pull the apron off and clean the half nut and gears. The half nut was plug up but cleaned up fine. Used WD-40 a solvent and when dry I used either 3-in-1 oil or lithium based white grease.

Is that 16T labelled little gear down on right side of aporn suppose to engage that long feed square cut screw on a contiunual basis? It was not engaged before so removed and bagged it.

This was a learning exercise for me. Thanks for all the good infor.

tim220225

My Feedback: (4)

Mike, here is the correct linck to the manual for the 7X10. http://www.harborfreight.com/cpi/cta...m&ItemID=93212 Sounds like a threading screw that was not engaged on your machine. On the bigger machines you have a thread dial made of cast iron that is removable. I would only use Way oil on the lathe ways or the lead screw. Grease will cake and pack chips in it. Some guys will use a lite straight grade engine oil also. Check the manual as you most likely have nylon gears. Also if the main headstock gear is nylon be careful as to how agressive a cut you take. If the lahe jams the headstock from turning you will break that gear.

captinjohn

I dis-engaged one of the gears so the lead screw did not run at all. I then tried to cut by turning carriage by hand. I soon found out I could not cut as nice as it cut using the live feed. It may be possible on aluminum with a more of a radius on cutting tool. I have to set up next with a more rounded tool...but I do not have it yet. You got to be on the "ball" when using live feed...you can crash into a revolving chuck! Capt,n

tim220225

My Feedback: (4)

Very tough to get a smooth cut by hand. Only time I try to is when I am approaching a shoulder or filet so I don't run the carriage into the part detail. Otherwise known as a mulligan.

captinjohn

Tim220225: I getting very mirror like finnish cuts by hand now. I did clean and adjust the ways and shimed the cutting tool dead center. Anyway...I am amazed how nice it cuts. Still having fun. Capt,n