Printable View
Although I'm not a big fan of lathe saddle stops I've got to the point where I thought it might be a good idea for certain repeat tasks and hence I've set out and made this for the Warco WM240B lathe.
Attachment 24861
The result is a cast iron block that hangs over the saddle and locks with a nut. The stop itself then is a threaded bar that has a simple locking knurled wheel. All quite simple to make and more details are here: Warco Saddle Stop
Hi Nigel:
Excellent design and finish of the components. I only have a suggestion for you. Any and all stops (lathe saddle, milling vise, etc.) are better provided with a round or convex contact area. The idea being that is easy for chips and any other debris, to stick to a flat surface messing up the accuracy of the location. Less so to the said end thus shaped.
Cheers
Jorge
There have been several stops posted that I have taken notice of, so by chance you are the one that I will ask sense I finally have enough motivation to post a question about them. I do not believe that I have yet seen a post that clearly shows how the stop clamps to the ways of the lathe. Perhaps a picture of the clamp side will be answer enough. Does the clamp or lock nut simply register on the underside of the ways? To be honest I have not owned my lathe long enough to have thought to look at the underside of the ways to see how much of a ledge is there. My lathe is a 12x32 enco of 1990 vintage. Just getting started with it. Finding out that "good condition" can have a more varied meaning than I would have thought. Oh well live and learn. Thanks in advance.
Eric
Most of the stop blocks I have used or encountered clamped like I have shown in the drawing picture
Attachment 24895
The basic block is milled to fit the way the clamp has a raised fulcrum to connect to the block held in place by a simple bolt from underneath
Some blocks will have the thread in the clamp and the bolt passing from the top .
the clamp will extend as far as required under the bottom of the way. usually depending on the size of the lathe it could be a little as .250" or as much as an inch or more.
Eric, good condition is a poorly over used term when someone sells a machine.
Particularly if they are not a machinist or have not operated the machine in question. To them good condition may mean everything moves or it switches on and runs.
Rarely if ever are any spec sheets supplied stating current tolerances, back lash, run-out etc
I've found some machines for sale claiming to have been refurbished only to find out the seller had done the refurbishment using little more than cleaning solvents and spray paint. I have even bought some if the price was right and the paint job was good quality, Knowing that as long as there wasn't too much wrong with it I could scrape square and tighten up where needed and make a decent machine out of it
How true it is Frank. The same word or definition, can have a different meaning for many people. That is akin as saying "an honest politician" when in fact is a contradiction in terms.
Cheers
George
Quote:
Originally Posted by editor@glue-it.com
Looks great, you did a nice job of it
Doug
<!-- BEGIN /var/www/html/homemadetools/protected/modules/zeus/views/tool/postUpdate.php -->
Thanks editor@glue-it.com! We've added your Lathe Saddle Stop to our Lathe Accessories category,
as well as to your builder page: editor@glue-it.com's Homemade Tools. Your receipt:
<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="http://www.homemadetools.net/homemade-lathe-saddle-stop-4"> <img src="/uploads/216312/homemade-lathe-saddle-stop-4.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="http://www.homemadetools.net/homemade-lathe-saddle-stop-4">Lathe Saddle Stop</a> <span> by <a href="http://www.homemadetools.net/builder/editor%40glue-it.com">editor@glue-it.com</a></span> </div> <div class="tags">tags: <a href='http://www.homemadetools.net/tag/lathe'>lathe</a>, <a href='http://www.homemadetools.net/tag/stop'>stop</a> </div> </div> </div> </div>
<!-- END /var/www/html/homemadetools/protected/modules/zeus/views/tool/postUpdate.php -->
I took the opportunity to stop by my shop while walking the dog to night. The ledge under the way on the lathe is 1/4 inch. Adequate I should think. But this brings up another question, the total depth of the ledge is actually 11/16. The difference is accounted for by the presence of a gear rack. Now I have yet to find an answer for the existence of 2 means of powering the carnage up and down the ways, lead screw and gear rack. Lead screw would be more accurate I am thinking. Could the gear rack be for broaching? Take more stress? It has much more lash than the screw. Is this some sort of chineesium lost in translation? I have down loaded the owners manual for the enco and the apparent grizzly clone but found nothing there. Any thoughts would be appreciated. Thanks
Eric
After a quick look the grizzly g4003 also has the rack. Must be some good reason for it just a newby to metal lathe work.
Eric
Apologies for my tardy reply, but I don't see any other answer to your question. I trust that your use of the word "carnage" is a typo and not an accurate reflection on the "good condition" machine you bought!Quote:
Originally Posted by suther51
Most "professional" manual lathes have both rack and leadscrew features fitted. Some very small lathes may dispense with the rack, and their leadscrews are permanently coupled to the saddle - a handwheel on the end of the leadscrew moves the carriage. Once we get to CNC machines, all bets are off.
RACK:
A handwheel on the apron drives the lathe saddle through some gearing which ends in the pinion that engages with the rack. This provides for "quick and dirty" movements of the saddle along the bed, irrespective of whether the lathe spindle is rotating or not. I have also seen some lathes with very heavy tailstocks equipped with a system for racking the tailstock roughly into position before using the tailstock quill for more finely controlled movement. On some very large machines, the rack movements may even be motorised.
LEADSCREW:
The leadscrew is usually coupled to a set of gears (often in a gearbox mounted in front of the headstock) that allows the leadscrew to rotate in a fixed ratio to the rotation of the lathe spindle - the ratio being set by the gear train selected. The apron usually carries a "split nut" mechanism which allows the lathe saddle to be coupled (or un-coupled) with the leadscrew as required. This is how we are able to cut threads and also provides for saddle fine feeds. Professional machines often save wear on the leadscrew by providing a separate saddle drive system.
So the short answer is: rack for quick and dirty movements, leadscrew for slower movements in direct ratio with spindle rotation.
Don't underestimate the potential of the handwheel-operated rack feed system. I have been able to produce balls of adequate quality when the quantities and time available did not warrant making a dedicated ball-turning attachment, by roughing out with combined cross- and rack feed and finishing with a file followed with an emery polish.
I hope this helps you.
Thank you for the reply. I likely did not articulate my question well, what confuses me is the ability to select power to the rack instead of the lead screw by flipping a lever on the apron. Powering the carriage with the lead screw makes scenes to me for accuracy. But when the rack is powered through the gear box the motion is jumpy and inconsistent. This all makes me wonder why some thing more than hand power on the rack might be needed. Thanks
Eric
Hi Eric,
I'm going to have to make a few educated guesses based on general practice, since I do not know the specifics of your machine, and I live in Germiston (part of the Greater Johannesburg metropolis), South Africa so I can't just "pop by".
In order for your saddle or carriage to move under power other than from the leadscrew via the half-nuts, a number of different systems were used, the most common of which were:
1. An additional shaft that runs parallel to the leadscrew rotates to transfer driving power through the saddle gears to the pinion which engages the rack, or
2. The leadscrew has a keyway along its length, and driving power is transferred through the saddle gears to the pinion which engages the rack.
These systems were intended to reduce the wear on the leadscrew when screwcutting was not required, since the leadscrew was originally made to fine tolerances to ensure consistently accurate threads. Depending on the complexity of the gear system in the saddle, a powered crossfeed was also possible. An interlock mechanism was necessary to prevent simultaneous engagement of the leadscrew and the rack-driven system - this is probably the lever you mention.
Your description: "when the rack is powered through the gear box the motion is jumpy and inconsistent" leads me to think that there is significant (= excessive) wear in that entire power train. Gear systems that are in good condition don't move in a jumpy and inconsistent manner. You can do basic troubleshooting by moving the carriage all the way to the tailstock end, where the rack would have had the least use, so you can assess the amount of wear on the pinion itself, as well as getting an idea of the wear in the bushes and other gears in the saddle system. You may have access to one of the USB "snake" cameras or endoscopes to help you see inside the saddle without taking it apart. Another indicator of whether the problem is isolated or throughout the rest of the machine is where was it used for most of its life - I wouldn't touch a machine that worked in a foundry, because dust mixed with lubricants makes grinding paste.
Ultimately, if you want to make any meaningful improvement, you will have to take it apart. My best advice in that case is find a friend who can help you, preferrably someone who has experience in the maintenance and repair of machinery, and access to some of the tools you'll need while your machine is out of commission.
Nothing is impossible, given enough money, time and patience, but you also need to assess your own motivations, and regularly re-evaluate them. If what is required is not worth the time, effort and money needed, cut your losses.
Hope this helps,
Russell (Papa Smurf)
Papa Smurf's descriptions are accurate. The 'lead screw', gear rack, 'feed rod' are as described, and each performs a distinct function.
Some lathes may have 1 or 2 more. One popular feature is a manually operated rod with stops or cams which trip a 'kick-out' for carriage travel.
Another rod, usually on long beds or heavier lathes with a motor & clutch arrangement to engage the spindle, some will even reverse. One is near headstock and bed, other travels with the carriage. Not only a safety feature, saves steps as well.
Import machinery tends to mimic and mix features their designer sees as worthy (if not dropped by accountants or marketing), that usually not had occurred in old iron. The imports realize this and put effort into what they want to sell; certainly some less successfully than others.
In years gone, a mix of features were geared to attract certain types and sizes of work shops. Most older businesses I've worked for, you'd see certain brands selected carefully, to take advantage of selling points. Those impressions bred preferences, and every thought used in assembling my shop too. Maybe I'd run 30+ different lathes, 20+ mills, who knows how many grinders....large or small. Like others, those experiences might become nostalgic, but rarely impulsive purchases.
Again I thank both of you for the responses. As this lathe is new to me and my memory is a bit questionable at times your comments and explanations have helped with my recall of my experimenting with the lathe. One lever on the carriage switches between the cross slide and the lead screw. If the cross slide is selected then a second lever alows the choice of power to be sent to the rack. Saving wear on the lead screw was one of the things I considered but I prefer not to make too many assumptions. While I may never do much more than farm equipment type repair with this machine I would like to be informed to a higher level. Thank you for the help, I shall tell both my father and my uncle of the reason for the power rack option. Unfortunately I may never learn enough due to lack of time to out grow this beat up lathe but I'm still ahead of those who may never run one at all. Thank you both
Eric
That you own a machine puts you ahead of an unfortunately large crowd.
Even without a machine tool, just being interested is still beyond that crowd.
That's what autodidact learning is all about, you learn by exposure and experimentation.
The gear rack is only used when you are turning the hand wheel on the side of the apron to traverse the entire carriage assembly manually.
Thank you for the responseQuote:
Originally Posted by owen moore
What had puzzled me was that there is the option to select power to the leadscrew or to the rack, two ways to move the apron under power. From the earlier replies it seems that the powered rack option is to save wear n tear on the leadscrew when not threading. Understandable but seemed a bit redundant. Happy building n doing
Eric
