Cross feed threaded rods??

First I'll say I am totally new. First post here and also my first machine is still in my truck in the crate waiting to be opened and cleaned and such before the first use.

What I have is a Grizzly.com G9729 Combo Lathe/Mill unit. I drove to the store and got it.
It's the best I could afford and looks decent.

However this model has a threaded rod for the cross feed that looks to be only about 3" threaded. Specs say "Cross slide travel: 3-3/4" "
The next model has a full feed acrossed, I think the bed on that one moves about 6-8" or even more.

How hard would it be to turn more threads in a cross feed rod like this? Or make a new one. I beleave this rod is what gives the measurements for turning depth also so it has to be pretty precise I think.

Also I had not thought of it till I got home with the machine, but if the table only feeds 3 3/4" and the tool rest is mounted on top of that table, does that mean I can only face a plate 3 3/4" at a time? Like a flywheel or other large diameter disk. My swing is supposed to be 16 1/2" so I figure in one pass I would need at least a 8 1/2" cross feed? Is that correct?
I will want to face 16" disks from edge to center and it does not seem correct to me that I would have to do half then reset the tool and start in the middle to get to the second half.

The salesman is checking to see if I can get a threaded rod from the larger unit and install that in this one, or the entire larger bed. However I expect it will be more of a buy it than them just giving it to me exchange, and probably expensive too.

I appreciate any help on how to fix this thread issue. If you want to see the machine and specs of what I bought I am posting the link for it. I think the parts list may be online also if anyone wants to look at the rod and see what I am talking about and how this one is setup. I don't plan to try turning it myself since I don't have a clue yet how to run this machine. If I should just make a new piece from blank rod I could try that in a few weeks or so and suggestions on that would be helpful also.

http://www.grizzly.com/products/item.cfm?itemnumber=g9729

Thanks

If you look at the picture of the toolpost and how far its jacked up above the compound, the additional swing they claim is gained via jacking up the headstock and tailstock instead of actually building a bigger lathe. Generally the cross-slide travel is going to be limited by the construction of the slide itself, and substituting a longer leadscrew most likely won't gain you anything. The limit of travel in the outward direction on most smaller lathes is when the slide backs out far enough to interfere with the handwheel. If you look at Grizzly's 14x40 lathe, which will swing 20" in the gap, it still has only 7" of cross slide travel, and it would have a substantially wider bed (a limiting factor in determining cross slide travel). Sorry, but I don't think there's a simple answer to what you're trying to do with this machine.

I would roughly guess that you cannot modify this lathe and need to buy the next model, so don't even uncrate it.

But i am not into small machines like that, don't know anything about it.

If you need to cut something 16" in dia. you need to be able to travel 8" on the cross feed.

But don't take my word for it, just don't uncrate your new machine until you know more about it.

Give it back to the dealer. This is not easy to visualize, so don't worry about making mistakes, just keep the cost of your mistakes down to a minimum.

calling this a 16" lathe when the crossfeed is only 3 inches and a nickels worth is MISLEADING ADVERTISING, they re-invent machine description, essentially misusing ignorant customer's trust

if the crossfeed is 3" you essentially have a 6" swing lathe going by old standards

these guys invent new standards nobody knows anything about, methinks

Repower,
By aligning the compound in the same direction as the crosslide you can add the compound travel to the cross slide travel to work on larger diameters. I'm not familiar with that machine but It's worth a try. For facing, you could feed the cross slide it's full travel, then continue the facing with the compound travel. It's not an ideal work around, may or may not leave a step on the work piece, but it's worth a try.
Have fun with it & good luck!
Ed

Hmmm..I wonder if there is a stop bolted to the underside of the table, or to the carriage.

Is there an exploded view you look at?

Enjoy your new toy

Alex

I will try to post a picture of the assembly and cross screw. working on it now, if I can upload it when done??

I have a 3-in-1 myself, a Shoptask, and have extended my cross travel a bit, although mine was 11" to begin with. Check to see what 'hits' at the far end of the travel in each direction. Typically the cross slide hand wheel will hit when the table moves in, but you need to see what hits when the table moves towards you. If the castings hit, well, that's all there is. But if you just run out of threaded portion on the acme feedscrew, it seems like a feedscrew with a longer threaded portion will gain you some travel. On mine I moved the handwheel out a bit by machining a spacer to go between it and the milling table, and added another spacer at the far end.

I don't see a way to upload a picture to the forum, does the forum alough the uploads or must I upload elsewhere and insert the url or just link to it?

I have a website I could upload to but I don't have the ftp running on this system I am using now.

Looking at the exploded view shows the short thread area on the begining of the shaft and lots of shaft beyond that with no threads. The feed handle is mounted to the end of the shaft, so it moves with the table, can't bump it. The feed shaft is mounted to the table on each end with heavy plates which hold the bearings and they hold the shaft. So the table is not moving on the shaft, the shaft moves with the table. Looks like a threaded nut or pipe type piece is what drives the table/shaft as it turns. I don't think that's a problem there. The dovetails are full length also.

Looks to me as if I could get the shaft out pretty easy, take out the allen screws holding the plates, let them swing down out of the way and slide off the table. Then I think there maybe a couple screws to remove and slide out the shaft.
Remove the handle too of course.

The shaft is turned down a couple steps on the handle end, otherwise it seems to be a straight shaft with threads for a few inches. All the way acrossed the top is a slot like a keyway.

Is this something I can make reasonably well myself once I learn to do such things, or is it such a close tolerance this machine would not be able to make one? Would it be a normal machineable steel I can work, or would I need to have it hardened or anything really difficult to prevent me from easily making one and changing it later?

This unit has a power crossfeed also. The next larger unit they sell has the full travel and is the same setup as this as far as we could tell looking at them, the shaft in that one has more threads. Looks like the table will work on either machine. So the thread area really seems to be the problem.
I can't see any reason they used such a short thread area here unless it was just to limit the crossfeed and try to bump you up to the larger machine to get more feed? It did cost $1,000 more.

I want to do alot of smaller items where the cross feed is fine and I can't find anything else that I can afford that does this much, so I will keep it anyway.

But does this sound like a item I should be able to make myself later or maybe have made for me by a real machist? Or is it something I would need to buy from the factory maybe?

"The feed handle is mounted to the end of the shaft, so it moves with the table, can't bump it."

That's the way mine is. The handle (or its mount) hits the undercarriage, when the table is all the way in. So, adding a spacer under the mount for the handle increases the cross travel by the thickness of the spacer. Adding a spacer at the other end between the bearing holder and the far end of the table increases the travel in that direction.

"The shaft is turned down a couple steps on the handle end, otherwise it seems to be a straight shaft with threads for a few inches. All the way across the top is a slot like a keyway."

The slot is probably how the cross feed is powered and is necessary. I would unhook the shaft as you mentioned, and slide the table back and forth to see how long the theoretical travel is.

If, and this is a BIG if, all you need to get more travel is a longer threaded portion on the shaft, you have a couple of options. First, I would talk to Grizzly, and see if their techs can determine if the shaft from the larger model will do the trick, sounds like you are already starting this approach.

Second, you can make one. Your cross feed shaft is what we call an acme threaded rod. It will be a standard acme thread of some sort, although it could be Metric or English. How many thousands of an inch does the feed travel with one revolution of the handwheel? If it is .100", you have an acme screw with 10 threads per inch, etc. Just look at the dial on the handle and see how much for each turn.

Then measure the diameter of the shaft. Mine is 3/4"-10. I would assume the folks at Grizzly can tell you what it is also. Then you would buy the correct acme shaft from McMaster-Carr, or Enco, etc. Most of the machining will just be various diameters at the ends to fit into the bearings, and can easily be done in the lathe. But milling the long slot will probably be too long to do in one pass on a 3-in-1, so you would need to figure out how to do it in several stages without losing register.

I'm in the early stages of lengthening my Shoptask's cross travel, so it is stuff I have been figuring out myself. I increased my cross travel about 3/4" with spacers as I described, but I would like to get more than the 12" I now have. In my case I am actually going to lengthen the table itself by adding a short section of another table, then machine a new acme shaft.

Dennis

Thanks for all the replies everyone.

Sorry, but it looked like I may have been waisting my time and yours, though I did get some good ideas to use later.

For some reason the catalod says the 3 3/4" cross feed and also the floor model at the store only had about 3 3/4" travel. BUT I un-crated mine today and after cleaning and finnally getting it ready to run I fired it up. I DO have about 8" cross feed
I checked this before turning it on. I had been grumbling a little about this and was showing the wife the machine when she asked what I had meant, when I tried to show her my 3" I was happy to find it was actually 8"

I was really surpised at this! As stated before the floor model at the store does not have this travel. I wonder if they relized the problem and updated the product but not the catalog nor floor model?? This was something that almost stopped me from buying it. I geuss sometimes not only can you not tell what you get for a machine when comparing different models and brands in cataogs, but you can not even tell when looking at them in person in the showroom either!

I am a very happy person right now

Glad to hear it, 8" is much better. I was a bit puzzled at the 3 3/4", since that would have given you an X-Y milling envelope of only 10" x 3 3/4" or so, and would have been the smallest envelope of the 3-in-1's.

I find lots of errors in specs for imported machines. Harbor Freight's nice big 20" drill press only lists a 3 5/8" quill travel. I measured the one in the store and it is really 5", a huge difference on a drill press. They would probably sell a heck of a lot more of them if they only listed the correct travel, since the stated travel is ridiculously small for that large of a drill press and really cripples it.

I bought Harbor Freight's large bead blast cabinet and it is excellent. It is far larger than their catalog states. I scaled the photo in the catalog and realized it was a nice size, so I called the warehouse and had a tech go and measure one, since they are catalog only. He managed to measure it wrong as it turns out, but it was even bigger than he thought!

Dennis

This is a super old thread but many guys find it when looking for info on Grizzly 3in1's so, I will add a little information to the thread. The cross slide is being confused with the compound which does travel the shorter distance. Likely a language translation issue.