# Inconsistent Cuts On Titan Lathe.



## c60 (Apr 6, 2016)

I got a Titan Lathe ( TL180V )secondhand just before Christmas. I've tried a few things with it but find it quite a finicky beast. It is nothing like the old Colchesters I remember from school days. My first issue is with just how speed sensitive it is. There seems to be no consistency between cutters even from the same set. The replaceable tip set seems to require higher speeds on brass than on alloy of the same diameter, just not logical.  

Specific issues - Anticipated speeds causes bad ribbing on brass, fine manual feed or auto feed. The only way to get anything like a cut is to run flat out. I am able to smooth this out with a Tubalcain shearing cutter copy in tool steel but a 4 inch length of brass supported with live centre has full length concavity. Cutting 9.5mm stock down to 8mm gives 8.12 live centre end, 8.07 at chuck end and 7.92 centre. I could understand if the middle bowed out due to flex in the stock bar.

Is it my tools? see image- cheap chinese supply, came used with the Lathe. I can't afford better. Is there something else going on? Thanks


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## Bob Korves (Apr 7, 2016)

A lot of the time those import brazed carbide tools are poorly ground, without sufficient relief so they end up rubbing on the work instead of cutting it.  You will need a carbide grinder to fix them IF that is the problem.  If they show signs of rubbing on the steel below the carbide you can grind away the offending steel.  Make sure your tool is set with the cutting edge at the center height of the work.

As to the insert tooling, that usually works well enough if the insert screw is tight and the tool cutting edge is truly on the center of the work.  Carbide likes high speeds and decent feeds with just about all materials.


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## c60 (Apr 7, 2016)

Thanks Bob. Unfortunately I don't think that is it. The brazed tools don't show any rubbing or scoring but are perhaps a little duller than I'd anticipate, even the ones unused prior. No protrusion of the relief. The insert type tools I've rotated to fresh points without benefit. The cut off version of this does have the holder protruding a little forward of the insert and I'll grind this as needed. I've been very careful on centering and have a selection of shims.  Cutting speed has been tested right up to 2500 rpm on ~9mm >4 brass and lubricant and 15mm>4 aluminium alloy with lubricant and insert cutters. Best (still poor) result has been at full speed with brass, guessing 2000 rpm on the alloy and average outcome.


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## atlas ten (Apr 7, 2016)

I would try a small radius on the cutter tip of the brazed tool bits. I use imported hss for most of my turning. With good finish on brass. Brass does need higher speeds to turn.
Jack

Sent from my SGH-I337M using Tapatalk


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## c60 (Apr 7, 2016)

Problem mostly resolved I think. I've tightened up the slack in the cross slide shims. I was using as purchased, (maybe a condition check on secondhand would have been a good idea in hindsight).  I think there was enough slack to push cutter below centre line under power hence the circumference ribbing. I'm getting a far better cut now and brass is good finish at around 1/3 of dial speed, no digital readout. Yet to check if the narrowing waist on long cut is also gone.

Jack - Have been thinking about a round tip for finishing, I'll make something if that mate of mine comes up with the promised tool steel. Looking for a simple grinding guide for it in the meantime.

Thanks for help and advice.


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## Bill Gruby (Apr 9, 2016)

My first question is "Where and why is the cross slide shimmed?" I would think that if shimmed too much the cross slide is less rigid. The fact that you were able to solve part of the problem by tightening them should be a heads up. I don't believe the problem is the tooling. I think it is in the cross slide itself somewhere. Just another idea to ponder.

 "Billy G"


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## c60 (Apr 9, 2016)

Good Question. I guess it is because it is a mainland Chinese Mini Lathe. Adjustment is very finicky and I'm not entirely convinced it removes all flex. But given the lathe part sizes and the cutting forces I'm not sure it is possible. I can't really complain as it was a case of "buy the Mill drill and I'll throw the lathe in for free" when I bought it.

I think the lathe may have a Grizzly badge equivalent. For shims see  items 94 and 107. I have a feeling there is a 3rd not shown that slides on main bed. The screws for that are a little more difficult to reach as it means removing the rear shield.


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## dkwflight (Apr 21, 2016)

Hi
I found my biggest issue was with proper grindinng the tool shape and putting the tool on or below center height .
Once a proper shape is done you will get good results.


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## Jinglz (Apr 26, 2016)

I bought a brand new Grizzly 7x14 and, after about a month of use, I started breaking every carbide tip tool I had. I thought it was part of the learning curve at first (I have more experience on much larger machines). But after not even being able to thread a piece of soft steel, I started to investigate my machine. 

I moved things around and checked tolerances only to find that I was getting about 1-3th inch deflection in my tip under load which is more than enough to break a carbide cutter.

I took everything apart and it turns out that all of the surfaces you can't see, like the bottom of the saddle/cross slide/compound, are given a rough surface grinding out of the cast. Which means everything fits together great but none of the parts are tuned to one another. I am in the process of tearing my entire machine down and lapping/honing everything in. While I am at it I am adding brass inserts to my gibs and SS bolts for all clamping surfaces. 

So far I have the saddle and cross slide lapped in using 220-400-600-1200-1600 (220-600-1600 would have been fine) grit so now all contact surfaces are smoother than glass. Before, they had the surface feel of a piece of corrugated cardboard with packing tape over it (you could feel the tool marks from the factory). Even though I still have a few more pieces to go, my god I can already feel a difference. I thought it was solid before but now... it feels like everything is welded together and moves with one finger. 

No matter what the condition new, used, or old I highly recommend taking the time to lap all of your surfaces in, especially with the Chinese machines. I know without a doubt the constancy of my cuts will increase 2-3 fold and if you are going to keep it around for a while invest the time now and it will pay for itself in the long run.


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## compsurge (Apr 26, 2016)

Jinglz said:


> I bought a brand new Grizzly 7x14 and, after about a month of use, I started breaking every carbide tip tool I had. I thought it was part of the learning curve at first (I have more experience on much larger machines). But after not even being able to thread a piece of soft steel, I started to investigate my machine.
> 
> I moved things around and checked tolerances only to find that I was getting about 1-3th inch deflection in my tip under load which is more than enough to break a carbide cutter.
> 
> ...



You want to make sure your sliding surfaces are actually not entirely smooth as the valleys in the surface hold oil. I definitely want to try lapping on a mini lathe my robotics team was donated. It could use some better contact patterning.


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## Jinglz (Apr 27, 2016)

compsurge said:


> You want to make sure your sliding surfaces are actually not entirely smooth as the valleys in the surface hold oil. I definitely want to try lapping on a mini lathe my robotics team was donated. It could use some better contact patterning.


Good call. I forgot to mention this. I polished only one side of each contacting pair for this reason. The lathe bed, contact surfaces for the cross slide and compound rest have minor surface deviations from the original manufacturer that will hold oil for me. That way the two can mature together.


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