doublegunshop.com - home Forums General Discussion DIY Gunsmithing @ doublegunshop.com Grizzly G8688 - 7" x 12" Mini Metal Lathe

I'm not up on the right terms but everything that is driven by Acme thread has a split nut that contact presure is adjustable. Making it tighter will take out the slop. It's explained in the manual.

I don't have one of these lathes, but I don't believe either the cross slide or compound have "split nuts". The only "split nut" should be in the carriage to operate the auto feed and for chasing threads. The "slop" would be taken up by adjusting the gibs in the cross/compound slides, and by adjusting the tension on the "screws" that drive them( where the handles attach); sometimes, a shim may be required. The best thing to do would be to get "face to face" help from a hobby Machinist/gunsmith. The manual is likely translated from Chinese by an office worker that doesn't know lathes.

Mike

These are the reasons I chose the 9 x 20 over the 7x12 firstly the drive system is all belt driven for the speed changes and not motor driven with a speed controller card that burns up if you get a major turning jam up. Next the tail stock can be set over for taper turning, but more importantly you can adjust the tailstock laterally for true parallel turning over the full length of the bed. My machine will cut imperial and metric threads though not the complete range of each but enough to get along with. The lathe has fine feed and threading leavers that work independently of each other. I have mentioned that the machine is in many ways more robust than the 7x12 and the extra size is very useful, because we all aske our machines to handle larger items that they are really not designed to undertake. The cross slide does have an adjustment to remove back lash, but the top slide does not. One not so good thing the feed screw nuts on the slides are Aluminium, but on my lathe the threads are a standard and available in engineer�s tap sizes though one is a left-hand thread, so I remade each using bronze. The head stock has number 3 Morse taper so you can purchase off the shelf collets that do not cost an arm and a leg. The spindle nose is threaded so changing from a 4 jaw to a 3 jaw chuck is quicker than undoing screws, and just for my personal liking I can fit a six inch 4 jaw chuck on the lathe for those larger projects. There are aa number of flaws with the machine all of them correctable and there are a number of web sites that go through all the modification that you can make to improve its overall working, but none of the mods are rocket science. As for taking back lash out of slide feed screws there are many methods from having two nuts and adjusting the timing been each along the thread of the feed screw found on expensive lathes, my 9x20 cross slide uses the nut tilt method using a separate screw to perform the tilting action. Another method is to cut the nut half way through and squeeze it length wise by doing this you alter the screw timing this can also be found on lathes made to look good on the second user resale market. Split nuts are found in the lathe apron used for engaging and disengaging the apron from the lead screw or the fine feed lead screw if the lathe has one.

damascus,
That is all true, but the 9x20s have problems of their own. My 6x18,12x36(both Craftsman and Clausing), and 16x60 South Bend, all have some type problem. Each of us selects our lathes based on need, availability, and affordability. The 7x12" lathes will never be a LeBlond, or Monarch; but they make a good learning vehicle, as do the 9x20s.One day, you may decide to do barrel work and would need a 12x36(maybe10x33), with a much slower speed than the 130rpm of the 9x20. In this case, buy a new one and be thankful for what you learned on the old one. BTW, there are very nice English lathes you can choose from, you are not limited to the ones I cited.
Mike

Der Ami
I spent most of my working carrier with machine tools especially lathes from CNC's capstan's to Boley watchmakers miniatures. But my decision was made on what lathe I would want to own in my retirement. A one and a half ton Boxford would be nice to own but my workshop is a little small for that sort of thing plus the delivery cost would be a little high. Also it would be problematical for the lady I live with when I go to that large engineering works in the sky to dispose of it. I also mentioned that my other interest is clock making and large lathes make that rather difficult indeed because their inaccuracy tolerance can be larger than the part you are making. The perfect lathe is available but that will depend how deep your pockets are but there comes the point where the higher the purchase price then in steps the law of diminishing returns do you need all those bells and whistles? I gave my reasons why I purchased the 9x20 but I did leave out that my model 9x20's is fitted with a Norton screw cutting gear box is it possible that you can find fault with this very useful addition for the price. Oh undertaking barrel work in the UK as a private individual is rather a tricky business and not looked kindly on here by the powers that be. To use a colloquial English term "plod would be quickly round to feel your collar and you feet wouldn't touch the floor till the cell door slammed behind you". On your side of the pond can do any engineering work to a fire arm with impunity, that is not the case here we have proof laws to contend with. Correct me if I am wrong I thought this posting was what people thought about the grizzly G8688 7x12 lathe and I gave my opinion and recommended the 7x20 for the reasons given. And finally If I wanted access to a larger lathe I would visit a friends engineering works on a Sunday and help my self.
And just to make things clear what is your opinion and reasons for it on the Grizzly 7x12 lathe because as far as I can see you seem to be on a points scoring mission on yours truly, So just stick to answering the question asked. Because as far as using a lathe and any other production machine tooling is concerned "I've been there done that and have the 'T' shirt, well having 50 years in production engineering does teach you a thing or six.

damascus,
If I gave you the erroneous impression that I'm trying to score points against you, I'm sorry. Within your text, you more or less seem to support my point. If you go back to my first post in this thread, I started out giving support to the idea of a beginner using one of the 7x12s until something more is needed or desired. I mentioned, in this, a website that is dedicated to the 7x12,including very many improvements/modifications. Our backgrounds could hardly be more different. You spent your working career with machine tools, and I spent mine longing for machine tools to use. My main interest is guns, and yours is clocks( although you must be interested in guns, you are on this forum). Yet both of us have chosen machines that fit best, our particular circumstances and neither of us own one of the little lathes we are discussing( in the interest of full disclosure, I admit I did own one for half a day once, but traded it off before even setting it up).Some of the publications I read have articles on guns and on clocks. I have no interest in clocks, yet I often find things in the clock making articles that may help me in the work I am interested in. By the same token, the many improvements/modifications shown in the website about the 7x12s, can be very useful as ideas for my work as well. At the same time making the improvements serve to teach the new owner of a 7x12 how to use a lathe, how to "set it up" and how to know what the limitations are. This is why I can recommend using a 7x12 as a first lathe. Working the problems out will teach more about using it, than any book will. For those of us that didn't have a chance to be schooled in the use of machines, other than making our own mistakes and "chips", the best way to learn is to make friends with a retired machinist/gunsmith that is willing to help. I'm sorry I don't live close enough to you, that I could "pick your brain". I suggest you check the cited website out, I think you will find helpful ideas that can be adapted to your 9x20.
Mike

Mike some of us old folks can be a little thin skinned now and again I can now see where you are coming from.
Any way clocks and gun have a lot in common in their historic roots, clock and Lock makers had the skills and know how to make fast and reliable gun locks. And sadly, I was working in Birmingham during the 1960s removing machine tools from the many closing workshops in the gun quarter hence my great interest in guns.
And on a personal note clocks are sort of living things and when they stop they are not breathing and for all intense and purposes dead.
The clock in the photograph was invented by Mattheus Hipp a Swiss in 1838 for use in observatories using a ground battery to keep the pendulum moving controlled by a toggle runs for four years on four flashlight cells all made from scrap metal and twenty pound of scrap Mercury that came my way.




And this is my reason for interest in vintage guns my 1869 bar in wood Purdey.

damascus,
I agree. I'm not into clocks, because they are beyond my skill level. It is quite clear there is nothing wrong with your metal or wood working skills.
Mike

Now that we have that settled ^ here's an update on the mini lathe. According to my local HF store the Central Machinery lathe is not a stock item and is ordered from China as needed. Lead time 6 to 13 weeks. Must be a slow boat from China? Grizzly does have the G8688 in stock but delivery cost eats up the savings over original list price. After studying everything I could find on the 'net about these small machines, not just the 7" x 12" but the bigger ones up to the 18" bed, my conclusion is to use the cost of one of these as a down payment on a larger, more versatile machine. A practical example is this 13" x 40" from Detroit Machine Tools. Highly unlikely we'll outgrow this size machine and it comes with a huge assortment of accessories. Plus, we're close enough to Ann Arbor, MI to drive up and get it to save the cost and aggravation of delivery. In the meantime we'll keep using the machinery we have. It has worked for a long time and will continue to do so for just a while longer.

Hank

Sort of agree with Hank
Started with a quarter inch drill on a stand and a file.
Next was a miniature Unimat which was very useful and a great learning tool. Still the most accurate 3-Jaw chuck I have seen.
Next, a 6" Atlas which did not fit my learning curve and just did not do what I wanted.
Next was a lightly used 14x48" Clausing which I have not outgrown. Easier to use than the Atlas for small stuff and have not reached the limit of its capabilities.
Used each for several years and would not go back.
Chuck