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The 9x20 Mods Thread

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savarin

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  • My 9x20 has a couple of mods including a qctp and 4 bolt clamp for the top/compound slide.
    I have noticed there is still a fair bit of flex under some conditions, parting being one.
    The fixing bolt for the qctp is still the original skinny one but with spacers.
    I will be drilling and tapping the compound to take the 14mm fixing bolt which I hope will remove a fair bit of flex, making a delrin cross slide nut to help remove the excessive backlash currently there as another must be done fix.
    I'm considering making the pritkin donut as I believe this is another possible cure for flex.
    Has anyone here made one of these and how does it perform?
    I really like the system drawn up by multiball1 (on the yahoo group site) but dont think my current machining expertise is quite up to it yet but has anyone here made this version and if so does it live up to the designers statements?​

    Asian 9x20, some rusty files and a hammer

 
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SG51Buss

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Re: 9x20 tool post flex


  • Hi, savarin. I'm totally clueless about your machine, but maybe this can be of some help.

    I recall my dad having similar 'flexing' problems, especially with parting. He made a gooseneck parting holder, but still experienced that chatter. Fast-forward, I'm doing a rebuild/restore on the thing, and discover that the rocker post t-slot plate, concave seat washer, and compound top surface are all warped. Resurfaced them all and a lot of the 'flexing' went away. Now using a 0xa QCTP, with a t-nut cut with a slight 1/2° upsweep on the wings, and that totally fills the slot, and the thicker 10mm fixing stud, and now it's even more solid...​

    --- Steve

    Atlas/Craftsman 6x18 (101.07301) (bushing headstock)​
 

arvidj

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Gunrunner you need to order a set of these for the Z axis hand crank. Bill did you just spit coffee on your monitor? :rofl:

View attachment 253356
 
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John Hasler

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Gunrunner you need to order a set of these for the Z axis hand crank. Bill did you just spit coffee on your monitor? :rofl:

View attachment 253356
 
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SG51Buss

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Re: 9x20 tool post flex


  • I like that 'donut' upgrade project, especially his deflection test. May have to give that a try...​

    --- Steve

    Atlas/Craftsman 6x18 (101.07301) (bushing headstock)

 
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D

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Re: 9x20 tool post flex



Yes Charles, swapping the bolt to a larger one will cure your problem. The original smaller one cannot handle the heavy load put on it by the QCTP. The shims do nothing but take up the space. They do not add to the rigidity. Actually in your case they add to the flexibility of the unit. You are getting much better at your problem solving. The 9X20 is a good teacher.


"Billy G"​

Since others have to tolerate my weaknesses, it is only fair that I tolerate theirs: William Allen White

THE FIRST 5 DAYS AFTER THE WEEKEND ARE THE TOUGHEST.

There are those that see things that are and ask -- "Why"? There are others that see things that have not been and ask -- "Why Not"​
 
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lear133

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Re: 9x20 tool post flex


  • The donut mount is worthwhile. Mine was a good improvement but ultimately the compound is the enemy. Makinging a solid platform for the qctp and only using the compound when needed is a better solution on a 9x20. That let me start taking much heavier cuts and part larger diameter steel more successfully.​
 
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savarin

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Re: 9x20 tool post flex

Instead of just relying upon the 3 central bolts to pull the compound onto the donut would it be worthwhile to add a recessed bolt through the donut into each corner of the compound making a total of 7 bolts fixing it?​

Asian 9x20, some rusty files and a hammer
 
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savarin

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Re: 9x20 tool post flex


  • Re: 9x20 tool post flex
    At last I've finished it.
    Took longer than I thought as I had to make a couple of fittings and decide upon the order of work but only two days once I started.
    The first job was single point threading the 14mm shaft then drilling and tapping the bottom end 6mm.
    I made a test chunk with a 14x1.25 tapped hole to test the thread and it felt very good. (photos are too blurry to upload)
    Next I made some clamps and bored the compound 12mm then used the tap to finish the thread.
    tapping top slide.jpg

    Reassembled the compound with the new 14mm shaft and turned down a bolt head to make the spacer to (in my mind) strengthen the fitting.
    The drawing gives the dimensions
    parts.jpg

    bolt, spacer, countersunk 6mm bolt, bottom of compound showing the recess left after removing the original shaft.
    I countersunk the spacer with a walmart special countersink that I thought had no chance of doing the job but I was pleasantly surprised.
    countersinking.jpg

    The fixing from underneath, a tight fit and flat.
    underneath.jpg


    The whole unit is assembled with high strength lock tight so I hope I dont have to disassemble it in the close future.
    The first tryout was like chalk and cheese for flex compared with before so now its the turn of the donut then brass gibbs.
    I forgot to take a pic fully reassembled but we all know what it looks like.

    So much to do so little time.​
countersinking.jpg parts.jpg tapping top slide.jpg underneath.jpg
 
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savarin

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Re: 9x20 tool post flex


  • Got the donut finished (almost) today. The scale and rust on the outer surface of the plate I used took the edges of of 4 tool bits by the time I had it clean enough to work.

    donut.jpg
    Now to drill the holes but I dont have any transfer punches and its sunday.
    So I annealed a cheap nail punch, turned it to the 7.3mm of the holes in the original degree disk, then hardened it again.

    transfer punch.jpg

    It worked. I drilled these holes at .2mm over size of the thread dia and they fit. They are not equi-spaced around the centre so the holes have to use the transfer punch.
    I'm now waiting for the high tensile button head screws so the counter bore is the minimum depth I can get to maximise the amount of metal left.

    donut2.jpg

    From the other side.
    I still think I will drill and tap the 4 corners of the compound to take 5mm dia high tensile bolts as I'm sure that will make it even more rigid as only 3 bolts in a small circle in the middle of the compound surely cannot be as rigid as more bolts spread over a larger area.

    donut1.jpg

    Asian 9x20, some rusty files and a hammer
donut.jpg donut2.jpg donut1.jpg transfer punch.jpg
 
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savarin

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Re: 9x20 tool post flex


  • Ouch! no shop time for 2 weeks but at last its finished.
    From underneath showing the counter bores. These were done with an old drill ground down to size with the angle grinder.
    donut bottom.jpg



    the inside of the donut and also showing the 4 extra tapped holes in the top slide.

    donut top.jpg


    All bolted up nice and tight and although I couldnt get an answer on the 4 extra bolts question I went with the assumption the 7 bolts is better then 3.
    bolted up.jpg
    All in place a clamped down. The large gap where the gibb strip is urgently needs filling with a new brass one.:makingdecision:

    in place.jpg

    My first test was to part some gummy hot rolled steel. Not a jot of judder, chatter, grabbing, stalling or whatever, it cut long rolled up strips of swarf the width of the blade. I was totally wrapped. I have never parted so effortlessly since I bought the lathe. :victory:
    All the apprehension I have suffered in the past with parting has now been put to rest.

    parting.jpg

    All I can say is dont waste your time with the 4 bolt ring clamp like I did go straight for this its the real business.
    I am now of the firm belief that this is the very first mod that should be done to this machine.
    The difference between before and after is like chalk and cheese
    I think this warrants making a plinth as well as suggested by "lear133"

    Asian 9x20, some rusty files and a hammer

parting.jpg in place.jpg donut bottom.jpg donut top.jpg bolted up.jpg
 
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savarin

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Re: 9x20 tool post flex

Well, the pics are back but for some reason they all added themselves at the end of the first post I tried to edit.
Then when I tried to edit the second set firefox refused to load the page. Arghhhhhhhhhhhhhh. no patience to try again for the moment.
 
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Nelson

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Re: 9x20 tool post flex

Well, the pics are back but for some reason they all added themselves at the end of the first post I tried to edit.
Then when I tried to edit the second set firefox refused to load the page. Arghhhhhhhhhhhhhh. no patience to try again for the moment.

I spaced them out best I could. One is missing.

When you insert, select "insert image" then "insert" when you select the image, then hit "done".

That should do it.
 

savarin

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Re: 9x20 tool post flex

Many thanks Nels, thats as good as its going to get.
I wonder what happened and why to loose the images from my uploads.
 
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Re: 9x20 tool post flex

Boy am I glad this one is back.

"Billy G"
 
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Nelson

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Re: 9x20 tool post flex

Savarin,

you and others can still edit your posts to replace any lost photos.

Thanks.
 
D

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Re: 9x20 tool post flex

Let's take the Top Slide up one more level Charles. In replacing my Top Slide with one of Tool Steel I found another reason why I took it off in the first place.. It's the size of the hand wheel. I think we can boost the size to 3" diameter. By offsetting it and raising it up a bit using a 3 gear train it should be feasible. 3 Boston Gear G-175 spur gears should be perfect. I will post a print shortly and ask for thoughts.

"Billy G"
 
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Re: 9x20 tool post flex

Here it is. Thoughts please. All will be graciously accepted. One mistake, where it says Driver gear attached to Lead screw, it should say Driven Gear. The Drive Gear is at the hand wheel. Sorry for any confusion.

"Billy G"

102_0841 (900 x 598).jpg
 

wrmiller

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Re: 9x20 tool post flex

Hey Bill,

If you don't mind, I may borrow/adapt this idea for my small lathe as it is of a similar design. :)
 
D

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Re: 9x20 tool post flex

Use whatever you need. Mine is an adaption of one by George Thomas. It is in the "Model Engineers Workshop Manual". That one may work for you also.

"Billy G"
 

Ulma Doctor

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Re: 9x20 tool post flex

Beautiful work,Savarin!!!
:thumbsup2:
 

savarin

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Re: 9x20 tool post flex

Here it is. Thoughts please. All will be graciously accepted. One mistake, where it says Driver gear attached to Lead screw, it should say Driven Gear. The Drive Gear is at the hand wheel. Sorry for any confusion.

"Billy G"
Does not the gear train add to the backlash feel?
 

chips&more

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Re: 9x20 tool post flex

Here it is. Thoughts please. All will be graciously accepted. One mistake, where it says Driver gear attached to Lead screw, it should say Driven Gear. The Drive Gear is at the hand wheel. Sorry for any confusion.

"Billy G"

Bill, the larger handwheel is to increase resolution I take it? IMHO I would entertain a planetary gear train arrangement. Not so big and awkwardly offset. It would be in line with the existing feed screw and you could design in any ratio you want, like 2:1 or maybe even 10:1…Good Luck, Dave.
 

savarin

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Re: 9x20 tool post flex

Bill, the larger handwheel is to increase resolution I take it? IMHO I would entertain a planetary gear train arrangement. Not so big and awkwardly offset. It would be in line with the existing feed screw and you could design in any ratio you want, like 2:1 or maybe even 10:1…Good Luck, Dave.
Now thats a good idea, I'm actually playing with a dual speed focusser unit for my scope that uses that idea.
3 steel balls sitting against a smooth small dia shaft, the whole lot sitting inside a tapered hole. Turning the large shaft is a direct drive, turning the small dia shaft is the speed reduction.
I have some renderings I will try to upload if any interest.
 
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Re: 9x20 tool post flex

Bill, the larger handwheel is to increase resolution I take it? IMHO I would entertain a planetary gear train arrangement. Not so big and awkwardly offset. It would be in line with the existing feed screw and you could design in any ratio you want, like 2:1 or maybe even 10:1…Good Luck, Dave.
The reason for the larger handle and the offset is for easier use. The resolution will not change. The gears keep it 1:1. The offset itself gets it out of the way of the cross Slide handle. The handle is way too small for my big hands. The unit is not as big as you would expect.

"Billy G"
 
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Re: 9x20 tool post flex

Does not the gear train add to the backlash feel?
Won't know that till I try it Charles. I guess it depends on the depth of the gear mesh.

"Billy G"
 

chips&more

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Re: 9x20 tool post flex

The reason for the larger handle and the offset is for easier use. The resolution will not change. The gears keep it 1:1. The offset itself gets it out of the way of the cross Slide handle. The handle is way too small for my big hands. The unit is not as big as you would expect.

"Billy G"

Yes the ratio would/can be 1:1, but the handwheel is much bigger making the spaces between the graduations larger. That is increasing the resolution. So you can now add another level of graduations, like tenths. That again, is increasing the resolution. Let me think more on the small handwheel with too big a hand.
 
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