Another Lathe Selection Thread

[Danuzzo]

I must preface this by saying that I have never built a model engine; but, I am very interested in the prospect of doing so. I want a lathe to start; however, I am basically going back and forth on which to buy. I need your help. I done extensive research on this forum and others, and am still at a loss.

I do have some machine shop experience from many years past so I do kind of know how to operate a lathe. Of course, I do want a lathe capable of building "small" model engines, including those that would require strict tolerances. The question then becomes what is a "small" model engine. Any help in identifying "small" by approx. dimensions would be helpful, particularly with regard to piston and cylinder dimensions.

I am interested in the 7x, 8x and 9x sizes. The only added interest in the 8x and 9x sizes is based on the weight differences which might possibly(??) be helpful with tighter tolerances. Heck, I am even considering a Sherline or a Taig, if those would be adequate. But, please note that I want to also be able to cut steel and cast iron on whatever I decide upon.

Help would be appreciated. Feel free to ask me anything you need to help me

 

[Rod Cole]

I'm expecting any day now, a truck with a new Acra 14 - 40. it took a while to decide, I just got tired of old high end, partly worn out, American machines~

 

[Danuzzo]

I'm expecting any day now, a truck with a new Acra 14 - 40. it took a while to decide, I just got tired of old high end, partly worn out, American machines~

Congratulations.

 

[Rod Cole]

One thing to watch for, as the lathe gets bigger, the spindle speeds offered get slower. This forum is not about production, so we might not need all that much speed, but we do need to remember, in order to get the "feet per minute" of small diameter parts in the range of cutting speed, we need some rpm~

 

[Danuzzo]

One thing to watch for, as the lathe gets bigger, the spindle speeds offered get slower. This forum is not about production, so we might not need all that much speed, but we do need to remember, in order to get the "feet per minute" of small diameter parts in the range of cutting speed, we need some rpm~

Thank's. I am more inclined toward the smaller lathes for mobility and space considerations. But, I still don't know.

 

[Brian Hein]

Thank's. I am more inclined toward the smaller lathes for mobility and space considerations. But, I still don't know.

I'm just going to chime in with a picture of my lathe. I searched for almost a year till I decided to import this from China. I had a very tight budget so my options were very limited. This is an 8 x 16 model. I has some limitations since its only about 100 lbs. It will take a bit of work to get it usable. You're basically buying a set of castings that require alot of tuning and adjusting so its usable, however, ther is lots of info on youtube to perform the needed tasks. I've had mine for just over a year and although I still find places it needs attention, it is quite usable.
Not sure if this helps or not

 

[Danuzzo]

I'm just going to chime in with a picture of my lathe. I searched for almost a year till I decided to import this from China. I had a very tight budget so my options were very limited. This is an 8 x 16 model. I has some limitations since its only about 100 lbs. It will take a bit of work to get it usable. You're basically buying a set of castings that require alot of tuning and adjusting so its usable, however, ther is lots of info on youtube to perform the needed tasks. I've had mine for just over a year and although I still find places it needs attention, it is quite usable.
Not sure if this helps or not

Thank's. Looks like a very nice lathe. How does it do on steel or cast iron?

 

[Brian Hein]

Thank's. Looks like a very nice lathe. How does it do on steel or cast iron?

I have turned cast iron with ease. I made a ER32 collet chuck for the lathe from a piece of 4140 shaft and that pushed the lathe to its limits. As long as you have the time to take small cuts (some material .25 mm at a time) it works well. I really like the variable speed control to adjust as you cut.

 

[Danuzzo]

Thank's again, Brian.

 

[clockworkcheval]

My suggestion is to buy anything that allows the biggest precision dimensions e.g. cylinders you have in mind, and buy a TAIG or similar for the small stuff where you need revs for the cutting speed. For the bigger stuff you may find that precision is less of an issue e.g with flywheels. Whenever this occurs you can either outsource or buy a cheap larger capacity lathe.

 

[Danuzzo]

My suggestion is to buy anything that allows the biggest precision dimensions e.g. cylinders you have in mind, and buy a TAIG or similar for the small stuff where you need revs for the cutting speed. For the bigger stuff you may find that precision is less of an issue e.g with flywheels. Whenever this occurs you can either outsource or buy a cheap larger capacity lathe.

Thank's. One of my questions would be the typical size of a "small" engine's cylinder.

 

[awake]

I'm lucky enough to have two lathes, a 12-1/2 x 30 Cincinnati TrayTop (around 70 years old, 1800 lbs.) - well worn, but still can do a lot of work, even including some surprisingly small parts (particularly since I use HSS tooling almost exclusively).

But I also have an import 7 x 14 that I picked up for $50 - how could I say no to that? Of course, the reason it was for sale cheap was that it had been partially damaged in a fire that messed up the motor and controller and change gears, but fortunately the structure was okay, and once I repaired and fixed it up, it is capable of very precise work. I use this for some of the really tiny stuff where I need high RPM.

The cylinder for my one-and-only build to date, a Webster, is .875" ID x 1.25" OD in its largest section (most of it is 1.075" OD) - but that is just the cylinder, not counting the cooling fins. I made those out of a separate piece of aluminum, 1.75" OD. With either of these, I could have done them on the 7 x 14 ... but I'm very glad I was able to do them instead on the TrayTop!

On the 7 x 14, a major issue would be that the material could not fit down into the chuck; it would all have to "hang out" from the chuck jaws. This reduces rigidity, which in turn further reduces the DOC that is possible or wise to take with each pass, and it may lead to problems with having enough room for the tailstock with drill chuck and drill - and with that in mind, if you go with a 7 x machine, make sure it is as long as you can get, at least x 14; whatever you do, do not get a 7 x 1o, because you will have a very hard time ever drilling anything!

If you can only have one lathe, and it needs to be semi-portable / bench-top, I would suggest looking in the 9 x 20 or 10 x 22-24 range - starting to get large enough to handle the larger parts more easily, but still small enough to place on a bench top. That said, I have no personal experience with any machines in this size, so I can't comment on which ones would be most worth looking at ...

 

[clockworkcheval]

Most models can be built with a piston dia of 25 mm/ 1", what even a TAIG or like will handle. But there is no real alternative to flipping thru models on internet, roadshows or musea, decide what you like and what you are going to build (may not be the same) and size your machinetools accordingly. Beware that tooling of a lathe or mill can equal easily the cost of the base machine. So probably the possibilities will have more impact on your choice than size. Possibilities as precision, threadcutting, bore dia of spindle, dia at headstock, possibility of copying a profile or cone, ease of conversion to CNC.

 

[user 1616]

Just want to ask if you are located near South Louisiana. I have a HF 9x20 Lathe, HF mini mill, and a Craftsman Atlas lathe sitting on the shelves as display items. Each works but need a little cleaning to remove the dust and I can tell you what mechanical is needed. Anyway, let me know if you are close.

 

[bluejets]

What may seem perfect for turning pistons, barrels etc. is , in many instances too small to spin a casting or whatever for a crankcase.
If not on the first engine in this instance, then for any future project.
Always think ahead.
Accuracy of any lathe is not so much in the structure of the machine but rather the "nut at the wheel".

 

[Danuzzo]

Just want to ask if you are located near South Louisiana. I have a HF 9x20 Lathe, HF mini mill, and a Craftsman Atlas lathe sitting on the shelves as display items. Each works but need a little cleaning to remove the dust and I can tell you what mechanical is needed. Anyway, let me know if you are close.

Thank's, but I am nowhere near there.

 

[Niels Abildgaard]

I have had a 7*12 lathe and with some rebuilding it is astonnishing

 

[Danuzzo]

Niels, was that your lathe in the video? Never seen anything like that one. What was it, and what did you do to it for rebuild?

EDIT: I answered my own questions by going directly to Youtube. Nice rebuild. I checked out one of your other Youtube video on the description.

 

[Niels Abildgaard]

There is a more detailed describtion of the rebuild here and more pictures

https://www.model-engineer.co.uk/forums/postings.asp?th=141922

 

[accelo]

I am a fan of the Sherline. I purchased one used on a whim. I have found it very capable and fun to use.
I also had one of the China imports a 7" X 12" I believe. I hated it. Plastic handles and handles that ran into each other.
One couldn't drill a hole it a part that was more than 2 inches long as I ran out of tail stock room.
I found if one purchases the extra length bed the Sherline was plenty long to do anything I wanted to.
Check out Luiz Ally's YouTube channel for examples of what can be done on the Sherlines.
Rick