# Compound slide not good.



## lesrhorer (Sep 19, 2021)

On my Vevor Lathe, the compound slide has both its travel and rigidity severely limited by the fact the dovetails and / or ways are not properly parallel.  If I move the slide to its middle position and properly set the gib screws so the slide moves easily but is still acceptably rigid, then the rear 1/3 of its travel is incredibly sloppy, with more than 0.020" slack.  If /I set the gibs at the rear 1/3 of the travel, the slide siezes by the time it is in the center of its travel.  Even if I loosen the gib screws entirely, the slide siezes before it reaches its farthest excursion forward.  Even a lathe this small (200 x 750 mm) should have a practical compound slide travel of more than 12mm, but this one does not.  The gib is far from perfect, but I don't see how it could be responsible for the evident taper, at least not by itself.

The dovetails are not ground.  It seems to me they, or at least the ways, should be ground and then lapped and /or scraped.  The milling marks are not very fine, at all.  I think I can help significantly by merely re-milling the dovetails.  It may not be worth it, but I think the dovetails and the ways should at least be ground, as well.  Is there someone out there with a surface grinder who could grind the dovetails, or at the very least the ways and the gib?


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## Winegrower (Sep 19, 2021)

I agree with re-milling the dovetails.   I had this problem when I first got my Logan 10".    It was an easy and very successful fix.   Obviously only the lightest touch is needed.    Didn't surface grind, didn't need to.   Now that I have a surface grinder, I still probably wouldn't.   I'm still at the point I can do a lot of damage with the grinder.


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## jwmay (Sep 19, 2021)

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Maybe call this company.


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## woodchucker (Sep 19, 2021)

Winegrower said:


> I agree with re-milling the dovetails.   I had this problem when I first got my Logan 10".    It was an easy and very successful fix.   Obviously only the lightest touch is needed.    Didn't surface grind, didn't need to.   Now that I have a surface grinder, I still probably wouldn't.   I'm still at the point I can do a lot of damage with the grinder.


wait... you can do a lot of damage with a grinder but not a mill?

for me it takes way longer to grind than mill. At any rate... I don't know of dovetails being lapped.. scraped yes.
do you have any idea how much you are out by?

do you have a machinery's handbook? in it it explains how to use pins to measure inside and outside the dovetails. You may want to read that and check so you know how much you are out by.  Once you have done that you can determine what the next step is.

You may even be able to stone it by hand to bring it in close.  Richard King is the man to talk to once you have your measurements.


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## lesrhorer (Sep 20, 2021)

Yes, I know how to measure dovetails, but I do not have any roller pins.  No, I don't have a Machinery's Handbook.


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## Winegrower (Sep 20, 2021)

woodchucker said:


> wait... you can do a lot of damage with a grinder but not a mill?


You do not know me, apparently.


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## Janderso (Sep 20, 2021)

lesrhorer said:


> The dovetails are not ground. It seems to me they, or at least the ways, should be ground and then lapped and /or scraped


Takes too much time, costs too much money.

We see this all the time on the Asian imports.
Like so many have said before, you are buying a kit that has to be finished.
Keep us along for the ride.
Love to see how it works out.

How to measure dovetails>>>


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## lesrhorer (Sep 20, 2021)

Thanks.  As I said before, I already know how to measure the dovetails, I just don't have any dowel pins.


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## lesrhorer (Sep 20, 2021)

The gib was pretty messed up.  The divots for the gib screws were incredibly sloppy.  All three were way off axis.  One was so far off the gib screw did not even touch it.  They were doing a terribly poor job of keeping the gib in place, and there was a great deal of anomalous vertical force when the screws were tightened.  I machined an Aluminum bar flat and glued the front of the gib to the bar.  I took a 6mm end mill and cleaned up the divots.  Now the force vectors shoud be uniform.  Below you can see how far off and non-uniform the divots were.  The bar is slightly banana shaped, and the thickness varies by about 15 tenths.  'Not great, but the front of the bar seems flatter than the back.  OTOH, it is concave on the front of the bar, which is less preferred to my way of thinking. I don't have any good way to actually measure flatness.  I am just going by the fact the bar spins on its center when pllaced on its back on a reasonably flat surface, and one can see light between the surface and the bar.  I did hand lap the front of the bar a little bit, but I don't have any good means to do much more than that.


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## lesrhorer (Sep 20, 2021)

I have ordered a set of dowel pins.  They should be here this week or early next week at the latest.


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## WobblyHand (Sep 20, 2021)

lesrhorer said:


> Yes, I know how to measure dovetails, but I do not have any roller pins.  No, I don't have a Machinery's Handbook.


When you get a chance, pick up a copy of Machinery's Handbook.  Just checked eBay, some under $20.  Well worth that.  A treasure of knowledge.  Get an older one.  Mine, a 19th edition, was published in 1964.  Anything between the 40's and 60's should serve you well.


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## woodchucker (Sep 20, 2021)

good, you'll need them as a starting point.  from machinery's handbook 18th edition


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## Janderso (Sep 20, 2021)

lesrhorer said:


> Thanks.  As I said before, I already know how to measure the dovetails, I just don't have any dowel pins.


oops.


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## woodchucker (Sep 20, 2021)

Janderso said:


> oops.


yea, somebodies a little testy... maybe he needs a time out...


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## Richard King 2 (Sep 20, 2021)

There is an old member who is retired and lives in San Antonio who I bet would love to help you.  His dad used to build new lathes and I believe he still has a machine shop.   I also taught a scraping class at Cox Manufacturing in San Antonio.   I taught them to scrape screw machine cross-slides.


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## Richard King 2 (Sep 20, 2021)

If anyone wants to learn how to scrape a compound, let me know.  It's  easy once you have the right tools and teacher.  Janderson can.  He had a couple of good teachers


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## lesrhorer (Sep 20, 2021)

woodchucker said:


> yea, somebodies a little testy... maybe he needs a time out...


I simply do not like having to repeat myself.  It means the other person has not read what I wrote, which far too often means they just have not bothered to read what I wrote.  I hate that.  Everyone makes mistakes, me more than most, and I am very tolerant  of human error.  I am not tolerant of laziness, however.  I am not accusing anyone in particular of anything, but I make my best effort to be certain of what other people take the time to write, and I expect the same consideration. I also take great pains to write accurately and succinctly.  Whenever I find myself repeating something I have already clearly stated, I am not happy, no.  I do not think that requires a time out.


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## lesrhorer (Sep 20, 2021)

WobblyHand said:


> When you get a chance, pick up a copy of Machinery's Handbook.  Just checked eBay, some under $20.  Well worth that.  A treasure of knowledge.  Get an older one.  Mine, a 19th edition, was published in 1964.  Anything between the 40's and 60's should serve you well.


I intend to do just that.  I did not know they could be had for $20.  Of course, gently used is perfectly fine.  They should sell electronic copies.  For one thing, one can't get oil all over a digital copy, and I won't have to search all over the shop to find where I last had it.  The best thing, however, is the ability to search digitally.


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## lesrhorer (Sep 20, 2021)

After cleaning up the gib by hand, the slide is far, far better.  It still gets very tight near the far end of the travel, but now doesn't sieze entirely.  I am also now able to remove much of the slop at the near end of the slide.  It still exhibits a 0.003" movement at the edge of the tool post, but that is a small fraction of what it was.  I still cannot call it good, but for many purposes it is good enough.  Single point threading, for example, only requires typically less than 0.100" of travel on the compound, and I can work near the far end of its travel to provide enough rigidity.  It s good enough for a cosmetic taper.  Forget about trying to re-create an R8, JT, or MT taper on a tool, though.


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## WesPete66 (Sep 20, 2021)

lesrhorer said:


> They should sell electronic copies.  For one thing, one can't get oil all over a digital copy, and I won't have to search all over the shop to find where I last had it.  The best thing, however, is the ability to search digitally.


I believe that a digital copy is available for sale.  But of course at publisher new prices..


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## Winegrower (Sep 20, 2021)

lesrhorer said:


> I simply do not like having to repeat myself. It means the other person has not read what I wrote, which far too often means they just have not bothered to read what I wrote.


If I start a thread asking for help, nobody has to read it.   Nobody has to respond.  Nobody has to understand what I was talking about.   It could be that my writing is not that compelling or clear.  Maybe I'll just try harder next time.


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## lesrhorer (Sep 20, 2021)

It's available for $25.49 on Kindle.  The formulas are far too small to read on the Kindle app on a phone, but are fine on a PC using the cloud reader.


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## woodchucker (Sep 20, 2021)

lesrhorer said:


> I simply do not like having to repeat myself.  It means the other person has not read what I wrote, which far too often means they just have not bothered to read what I wrote.  I hate that.  Everyone makes mistakes, me more than most, and I am very tolerant  of human error.  I am not tolerant of laziness, however.  I am not accusing anyone in particular of anything, but I make my best effort to be certain of what other people take the time to write, and I expect the same consideration. I also take great pains to write accurately and succinctly.  Whenever I find myself repeating something I have already clearly stated, I am not happy, no.  I do not think that requires a time out.


apparently not too tolerant of human error. I also don't like when people don't read, but sometimes; its that we read it but forgot, our minds are already racing to other things, or some of us are older, and forget.

now if you want to get help, don't keep shooting the people trying to help... I think you shot twice. The third time you may have some shotguns pointing back at ya.


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## lesrhorer (Sep 20, 2021)

Winegrower said:


> If I start a thread asking for help, nobody has to read it.   Nobody has to respond.  Nobody has to understand what I was talking about.   It could be that my writing is not that compelling or clear.  Maybe I'll just try harder next time.


I follow your reasoning, but I don't really see how it is particularly pertinent.  Whether one is pleading for help or offering it, one is still due the amount of respect one earns.  I certainly am not trying to be a jerk, here, but answering the same question more than once is a waste of time, and so is asking it.  Certainly it is true one garners more flies with honey than vinegar, but one should not feel compelled to erode one's self respect in order to receive assistance.

I am quite certain Jeff did not intend any offense, nor anyone else here, but it is not a lot of help to tell someone something they already know.


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## Winegrower (Sep 20, 2021)

Winegrower out.


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## WobblyHand (Sep 20, 2021)

lesrhorer said:


> I intend to do just that.  I did not know they could be had for $20.  Of course, gently used is perfectly fine.  They should sell electronic copies.  For one thing, one can't get oil all over a digital copy, and I won't have to search all over the shop to find where I last had it.  The best thing, however, is the ability to search digitally.


You can get a brand new digital edition for $120.  Of course, that's a lot more than $20!


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## lesrhorer (Sep 20, 2021)

woodchucker said:


> apparently not too tolerant of human error.


I can't expect you to know anything about me, but actually, I am.  You may ask any of my former colleagues or my employees.  As a professional engineer, of course, I strongly dislike errors of any sort, but I go to great lengths to support and defend those who make an honest mistake.


woodchucker said:


> I also don't like when people don't read, but sometimes; its that we read it but forgot, our minds are already racing to other things, or some of us are older, and forget.


I doubt there are many people here much older than I.  There are a few, I am sure, but the number grows smaller every year.


woodchucker said:


> now if you want to get help, don't keep shooting the people trying to help... I think you shot twice.


I disagree.  I did not shoot even once.  Nothing I said was in any way caustic, disrespectful, dismissive, or vituperative.  I most certainly did not engage in any personal attack.


woodchucker said:


> The third time you may have some shotguns pointing back at ya.


I have been shot at by people with real guns.  After nearly 40 years working as a physicist and an engineer, any changes to my character are not terribly likely, especially not ones that I feel would diminish my worth as a human being.  Others must judge this as they like.  I certainly enjoy getting help. and I enjoy even more helping others, but both must develop on my own terms, or not at all.  Again, I do not intend the fact to offend anyone at all, but if it does, it does.


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## lesrhorer (Sep 20, 2021)

WobblyHand said:


> You can get a brand new digital edition for $120.  Of course, that's a lot more than $20!


I never have liked that sort of math.  It hurts my wallet.  The Kindle edition is the 31st, which I believe is the latest.


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## MyLilMule (Jan 4, 2022)

lesrhorer said:


> It's available for $25.49 on Kindle.  The formulas are far too small to read on the Kindle app on a phone, but are fine on a PC using the cloud reader.


I believe you are referring to the GUIDE to the handbook, not the handbook itself.


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## addertooth (Jan 4, 2022)

Could you tell us which Vevor model it is?  It is possible replacement parts could be found for some models.
I see you gave 200 X 750 as the dimensions, which makes it roughly 7.87 X 13.4 inches.  In this case, the model number will help, as 
that size is "odd".   A picture of your lathe would probably be useful in this case. I am wondering if it is one of the 7 inch family lathes, like 
a Sieg SC2 which has been re-branded. What size is the chuck?
Do you know whether it is the upper or lower half of the compound blocks which has the error (taper)?


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## Richard King 2 (Jan 4, 2022)

I sell the new  Connelly Books on eBay.  I will give our members a 15 % discount. Also I would help in scraping the dovetails, but I won't get involved with the childish argument.  Private message me or start a new thread.  Asking a question on a open forum can be frustrating to a new member.  You have to be able to overlook advice from someone who guesses.


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## Richard King 2 (Jan 4, 2022)

Come over to the Machine reconditioning forum as many of us have gotten paid to measure and rebuild dovetail ways.








						ALL ABOUT MACHINE RESTORATION & WAY SCRAPING
					

Learn methods of restoring a machine to new or better performance through precision scraping of ways in this forum!




					www.hobby-machinist.com


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## Cadillac (Jan 4, 2022)

Here you go 28th edition. 
Machinery's Handbook Guide - 28th Edition (Malestrom)
Malestrom


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## ericc (Jan 4, 2022)

I just tried this test on my cross slide ways.  You don't need special pins if your cross slide has 20 thousandths of slop in it.  Even a pair of pins that you make yourself in the lathe should be accurate enough, especially if you have a sharpie available.  I was able to measure about 4 thousandths of wear.  I think you don't have to wait for your pin order to arrive.  There may be supply chain problems anyway.  For 20 thousandths, a couple of pencils would probably work.


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## Richard King 2 (Jan 6, 2022)

There is an easy way that many overlook.   Set the slides on a Mill , clamp down lightly or surface grinder mag down slightly and indicate it in on there.  Most mills and grinders are straight in 12"

Eric please be nice, we are trying to help.  Pencils won't work and if it moved .020" I suspect the gib was loose.


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## ericc (Jan 6, 2022)

Sorry, Richard.  But I was trying to be helpful.  I was thinking of those round giveaway pencils that you get at the county or library events.  I just measured one, and it was out of round by nearly 8 thou.  Still, if you put a dot with a sharpie on two pencil stubs and make sure they are clocked to the same place and you apply the calipers right on the dots, you should be good to within a few thou until the real dowel pins arrive.


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## Richard King 2 (Jan 7, 2022)

You can buy hardened dowel pins at a hardware store.  I won't help if your going to use a pencil.  This is precision rebuilding forum.


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## jwmay (Jan 9, 2022)

I'm not sure the OP ever came back. There was a miscommunication it seemed... or a misinterpretation? Either way, I don't believe we've seen him since. The person suggesting pencils isn't the one asking the original question.


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