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Hafco AL336 not cutting straight

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warrjon

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#1
Looking for a second opinion. I suspect the head stock is not lined up down the bed. I do not think it's cross slide as I have faced 3" aluminium and if the cross slide was not perpendicular to the ways I would machine a concave especially with this amount of slew nearly 0.10mm or 0.0035".

My lathe is adjustable but I decided to sleep on it before diving in and adjusting the head stock.
 

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markba633csi

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#3
Two things could in theory make you face concave (or convex),one is the cross slide not perpendicular to the ways, the other being the spindle not parallel to the ways. My bet, especially if your headstock is adjustable, is the headstock itself
Mark
 

pacifica

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#4
On my new 1340gt I was getting a taper, .005" over 5", spindle nose has less than .0001, ways were perfect, chuck was great.

I had to adjust the headstock. Put a 1.75" x 13" steel rod in chuck, stuck out 10" and trued the rod.

Moved the headstock a little at a time, very tedious and time consuming, because I took a .006" cut after every adjustment.

After 4 hours the taper was down to less than .0002" over 5"

If you put a dial indicator against the end of the rod it helps in adjusting. Very small movement .010 and less is best.

Don't use the tailstock.
 

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warrjon

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#5
Thanks Guys,

Yes the head stock is adjustable, but as with anything I have to pull the motor off to get to the adjusting bolts and the pulleys and gears off to get to the back mounting bolts. I'm beginning to regret selling my Sheraton 9", it cut straight less than 0.001mm over 250mm.

Oh well a little time on this and we'll see how it goes. This has not been a trouble free lathe it's on its 3rd motor. I can not sell it to some other poor person either as I would not sleep.

cheers
Warren
 

pacifica

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#6
Thanks Guys,

Yes the head stock is adjustable, but as with anything I have to pull the motor off to get to the adjusting bolts and the pulleys and gears off to get to the back mounting bolts. I'm beginning to regret selling my Sheraton 9", it cut straight less than 0.001mm over 250mm.

Oh well a little time on this and we'll see how it goes. This has not been a trouble free lathe it's on its 3rd motor. I can not sell it to some other poor person either as I would not sleep.

cheers
Warren
I had to remove the drive belt and slightly lower the motor each time I made an adjustment. 7 Bolts were all easy to get to. Even so, it took hours to zero in.

Probably a full day or two for your set-up.I did power up the lathe after each adjust and take a cut; if you could figure a way to measure without having to re-install the gears and motor?
 

warrjon

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#7
I spent yesterday afternoon adjusting the headstock, I used the Rollie's Dad's method, which I have never heard of before. I worked great in less than 2hrs I had it cutting 0.00078" over 5". It was better but I think the head stock moved a little when I tightened the bolts so now I know how the adjustment works I'll have another go this coming weekend.

I had to do the adhustment about 20 times as the headstock rotates at the back so you can not subtract the 2 measurements. Also there are 4 adjustment bolts 2 pull on the headstock and 2 push so they need to be tight against each other this way I think the headstock will not move when I tighten the bolts.

Anyway thanks ALL.
 

warrjon

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#8
Yesterday I tweaked it a little more it now cuts parallel.

I am still not very happy with this machine it faces concave which is not an easy fix. I faced a 300mm brake disc and on the surface plate it is 0.06mm from outer to inner. I'll have one more attempt at getting this thing to an acceptable level of accuracy before I ditch it.

I have spent more time trying to tune this thing up than making what I need. I will never buy another Hafco product.
 

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mikey

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#9
Just curious - are you using carbide tooling for your tests? If so, that can confuse things because of the deflection the tool produces at small depths of cut. Might want to try a sharp HSS tool instead.
 

pacifica

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Yesterday I tweaked it a little more it now cuts parallel.

I am still not very happy with this machine it faces concave which is not an easy fix. I faced a 300mm brake disc and on the surface plate it is 0.06mm from outer to inner. I'll have one more attempt at getting this thing to an acceptable level of accuracy before I ditch it.

I have spent more time trying to tune this thing up than making what I need. I will never buy another Hafco product.
Should be .01mm or less
 

warrjon

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#11
Thanks guys.

I used a HSS vertical sheer tool for the turning and carbide for the facing.

I had a quick look tonight and I've decided to go back and start again. I checked the runout on the spindle mounting face 0.01mm, pulled the jaws off the 3 jaw and checked the runout at the chuck face 0.05mm. Rotated the chuck in the spindle and the runout changed I got it down to 0.02mm. So this weekends job is to markup the spindle and check the mount, and put the chuck on the surface plate to check it.
 
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warrjon

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#12
Just thinking......

With the chuck not running concentric I think I have mal adjusted the headstock so it cuts parallel but the headstock is now pointing forward.
 

NortonDommi

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#13
I've got an AL356V and after about 3 years developed a slight taper, turned out the two front hold down bolts had relaxed slightly. Crap quality so replace all the cap screws with quality ones, aligned using Rollie's Dad's method with a cut on a 300mm piece of 50mm heavy wall pipe for final checks and been good last couple of years. The cap screws are all low quality throughout so it pays to replace as you go if you need to remove for any reason.
 

Downunder Bob

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#14
Have a look at Dgrev's post on his older hafco al 900. he has had no end of trouble getting it square.

Unfortunately hafco are selling a lot of chineses made stuff that has not been properly made or assembled. And it appears that they don't check them very well on delivery.

I only have one hafco product, a small band saw, it is Taiwanese made and it does a pretty good job so far, considering I overload it shamelessly.

If you get it to turn parallel and then it faces concave or convex, it means the cross slide is not square with the bed. you may also find that the head stock is not parallel in the horizontal plane and you may have to shim it. So when you have turned a piece that is reasonably parallel, set your dial indicator to read on the top of the shaft and wind the carriage back and forward see if its truly horizontal. If it dips or rises that will affect your parallel turning so shim that first and then reset the headstock square with the carriage travel.

Before buying my lathe I looked at these chinese made lathes, and walked away from them. A decent Taiwanese made lathe of the same size is only about 20% more to me that is no contest.

If the cross slide and bed turn out to be out of square you may have to compromise on each one. depends which one is more important for the work you do. good luck.
 
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pacifica

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#15
Just thinking......

With the chuck not running concentric I think I have mal adjusted the headstock so it cuts parallel but the headstock is now pointing forward.
When I adjusted my headstock the tailstock needed a big adjustment, too.

I wished I would have changed my cap screws with high quality screws, sometimes when I moved them the headstock moved opposite the way it should have. I believe this is due to uneven threads and/or unflat surfaces on the cap screws( either at the base or under the cap). Might also be due to uneven surfaces where the headstock meets the lathe bed.

Unfortunately it is true that before adjusting the headstock everything else(chuck or collets, bed, compound, carriage, crossslide, leveling, ) need to be dialed in.:guilty:
 

warrjon

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#16
I've got an AL356V and after about 3 years developed a slight taper, turned out the two front hold down bolts had relaxed slightly. Crap quality so replace all the cap screws with quality ones, aligned using Rollie's Dad's method with a cut on a 300mm piece of 50mm heavy wall pipe for final checks and been good last couple of years. The cap screws are all low quality throughout so it pays to replace as you go if you need to remove for any reason.
Thats a very good suggestion, I replaced the column bolts on my HM47 with 8.8 so I will do the same with the lathe this week.
 

warrjon

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#17
There is a Colchester for sale which I have already inquired about, I am seriously considering it.

My problem is I can not sell this lathe as it is. I would not pass this onto an unsuspecting buyer. I need to get it cutting as true as I can then re-asses. I have just ordered a Moore & Wright 0.001mm runout indicator and I have a 16x400mm precision shaft.
 

warrjon

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#18
I did the lathe cutting less than 0.02mm taper over 140mm, not too bad.

But I fixed the issue for good. I had been looking for a Colchester for a long time and this one came up, it's in very good condition, the bed looks pristine, even the brake works.

Colchester Master Mk1.5.jpg
 

Downunder Bob

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#19
You did well, lathes of this quality and in this condition are very scarce downunder. I looked for a couple of years and gave up, ended up buying new.
 

warrjon

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#20
I made the trip into Melbourne today to pick it up, I thought $3000 was a good price for the condition, most of the swarf in the machine is plastic.

As soon as the VFD arrives I can fire it up.
 

Downunder Bob

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#21
Good luck with the new machine.

As for the other one, obviously when the headstock is pointing towards the front or the back it will turn with a taper along the length, it will also result in a concave or convex face. What happens when you get the parallel bit right and you still have a convex or concave face. It would appear that you have corrected the parallel part by the wrong method.

You first need to confirm that the centerline of the headstock is parallel to the bed in the horizontal plane, that is, it is neither pointing up nor down. If it's pointing up or down that will cause it to turn tapered even when lined up correctly. So you need to correct the horizontal alignment first, by shimming under the headstock, so that the center line of the H/S is the same height above the bed along its length, or at least at both ends.

Once that is done then you can continue as before to correct the parallel turning in the normal way. This should result in the lathe turning parallel and square across teh face. If it does not then one would have to assume that the cross slide is not square to the bed. I don't know how you can correct that.
 

warrjon

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#22
I corrected the parallel part using Rollies dads method in both planes. I did shim under the front of the HS to get it level with the bed. This immediately had the lathe turning parallel within 0.02mm over 130mm with the larger collar at the TS end. The lathe cut a convex of 0.03mm on a 100mm diameter bar.

The issues are

1. I can not level the bed. I had the lathe bolted to the concrete floor on jacking bolts so I could easily level it. It needed the front TS end raised but this also moved the HS end out of level. With the HS end level (0.02mm/1m level) at the TS end the bubble was hard to the rear of the level.

2. Both chucks have the jaws splay so it is impossible to re-chuck something concentric.

3. The spindle nose has 0.01mm runout and possibly the cross slide is not at 90° to the bed.

I have indexed the chucks so the runout in the face is 0.01mm. New jaws may fix the splay issue but for the cost of new chucks I decided to buy the Colchester it still has its original Burnerd 4 jaw and a Burnerd 3 jaw so the cost of these would be nearly what I paid for the machine.

For hobby work I would have lived with it. It probably cuts as good as most cheap Chinese lathes but I am machining engine parts for a V12 Jaguar (pistons ATM) so I need the lathe to cut more accurately than it does.
 
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