Money to spend on inserts and holder for lathe

[animal12]

I gotto hang with Spring , If I hadn't bought a standard QCTP my lathe would be wearing one of the Chinese Multifix tool post . Yea their a bit more than a regular QCTP but I feel they are so much more versatile . We could setup a go-fund me to get me a Multifix & I will give a full rep[ort / review to this forum .
animal

 

[dazz]

Hmm- - - - please explicate - - - how does having a tool opposite the one in use on a 4-way toolpost improve rigidity?

The unused tool holder slightly bows the underside of the toolpost. The added leverage improves the clamping and effective rigidity.

 

[Neil Lickfold]

What I have found that adding another holder onto the tool block, even if empty, can alter the resonance. It only works if resonance becomes a problem.

 

[ajoeiam]

The unused tool holder slightly bows the underside of the toolpost. The added leverage improves the clamping and effective rigidity.

It would seem that you have a poor quality toolpost. If not having a tool in a side causes any measurable bowing - - - well - - - you've got a problem.
Dunno if its a case of the top and bottom members being inadequate or an inadequate grade of material (for the toolpost) but this does NOT need to be this way.
If you are getting bowing - - - it could also mean that you are over tightening the hold down screws on the toolpost.
(This not over tightening things has been something that I had to learn the hard way. I can remember snapping off the head of a 5/8" bolt using a standard combination wrench (15/16") (no cheater nor snipe) - - - - - that I could tighten the bolt to that level really didn't help me much!!)

 

[Steamchick]

Usually tool suppliers supply things with the correct sized wrench so you DO NOT, or cannot over tighten fixings.
That's why small spanners are shorter than big spanners...
K2

 

[ShopShoe]

ajoeiam,

"- - - how does having a tool opposite the one in use on a 4-way toolpost improve rigidity?"

The 4-way toolblock and mounting stud on 7x mini lathes of mine's vintage are too "flexible" to begin with. I also suspect that under cutting conditions they may oscillate (which is what chatter is.) So, the logic (which is not my original idea) is that equalizing stress on the block and "balancing" the assembly will reduce chatter and make it easier to keep the cutting edge(s) of the tool aligned when cutting. And, the cutting stresses change with the usual feeds and speeds and type of material being cut.

I will admit that other factors come into play, especially if I have the "wrong" toolbit or have it ground wrong or etc. or etc........

I have tested the "second toolbit installed opposite" theory on my lathe in my shop and it helps in my situation: Your mileage may vary...

I also made a "one toolbit" toolblock that was all solid except for a mounting slot for one toolbit and that performed better than the stock one.

When I got the QCTP, I found it came with a heavier mounting stud made of better material and just seemed to be more rigid in its construction. It is a wedge type toolpost, rather than a piston type, which was my preference. I can't comment on the performance with a piston type toolpost.

--ShopShoe

 

[Richard Hed]

ajoeiam,

"- - - how does having a tool opposite the one in use on a 4-way toolpost improve rigidity?"

The 4-way toolblock and mounting stud on 7x mini lathes of mine's vintage are too "flexible" to begin with. I also suspect that under cutting conditions they may oscillate (which is what chatter is.) So, the logic (which is not my original idea) is that equalizing stress on the block and "balancing" the assembly will reduce chatter and make it easier to keep the cutting edge(s) of the tool aligned when cutting. And, the cutting stresses change with the usual feeds and speeds and type of material being cut.

I will admit that other factors come into play, especially if I have the "wrong" toolbit or have it ground wrong or etc. or etc........

I have tested the "second toolbit installed opposite" theory on my lathe in my shop and it helps in my situation: Your mileage may vary...

I also made a "one toolbit" toolblock that was all solid except for a mounting slot for one toolbit and that performed better than the stock one.

When I got the QCTP, I found it came with a heavier mounting stud made of better material and just seemed to be more rigid in its construction. It is a wedge type toolpost, rather than a piston type, which was my preference. I can't comment on the performance with a piston type toolpost.

--ShopShoe

Allegedly the wedge type are better, but I wonder.

 

[awake]

Allegedly the wedge type are better, but I wonder.

They are ... but the piston type are 1) much easier to make, and 2) more than good enough for hobby level manual machining.

 

[ajoeiam]

ajoeiam,
snip

I also made a "one toolbit" toolblock that was all solid except for a mounting slot for one toolbit and that performed better than the stock one.

When I got the QCTP, I found it came with a heavier mounting stud made of better material and just seemed to be more rigid in its construction. It is a wedge type toolpost, rather than a piston type, which was my preference. I can't comment on the performance with a piston type toolpost.

--ShopShoe

The all solid toolblock would have a different resonant frequency when excited.

Finding the "heavier stud made of better material" - - - - "more rigid" would - - - imo anyway underscore what I was saying.
Its one of the problems with small very light duty machines - - - they are 'reasonable' because of more factors than just that they are small.

I'd bet any owner of a 10EE (or is it 10EEE) won't be talking about this kind of flexing - - -yet its the same size of machine.
(But most definitely not the 'class' of machine.)

(Its one of the reasons and older VDF lathe sells for more $$$ and faster than a newer Tos.
Either works - - - but the fit and finish on the VDF - - - - - well - - its like the difference between mitutoyo and starret mic compared to a Tesa - - -they are just not the same!

 

[ajoeiam]

They are ... but the piston type are 1) much easier to make, and 2) more than good enough for hobby level manual machining.

Even for 'fun' I just don't work to 'good enough'.
I no longer try to aim for 'perfect' but aiming for 'good enough' is going to get me into trouble.

The not pushing for perfection is something machining taught me.
Perfect is the enemy of acceptable - - - that's why machinists have tolerance bands and welders talk about 'dead nuts' (and they just don't get there but that's another story!!!).

 

[dazz]

It would seem that you have a poor quality toolpost. If not having a tool in a side causes any measurable bowing - - - well - - - you've got a problem.
Dunno if its a case of the top and bottom members being inadequate or an inadequate grade of material (for the toolpost) but this does NOT need to be this way.

The quality of steel does not affect the degree of flex (bowing). Quality does affect the ultimate yield point.
If force is applied to steel, or any material, it will flex.

If you are getting bowing - - - it could also mean that you are over tightening the hold down screws on the toolpost.
(This not over tightening things has been something that I had to learn the hard way. I can remember snapping off the head of a 5/8" bolt using a standard combination wrench (15/16") (no cheater nor snipe) - - - - - that I could tighten the bolt to that level really didn't help me much!!)

It is a small, light duty lathe. It is going to flex when something is tightened.

 

[David Shealey]

The Quick Change posts wi all interchange with each other as far as I've found. I have tool holders from 4 different makers and all enterchanable.

Correct. I have a Chinese 250 size (BXA) Aloris wedge style, and holders from three different sources. All fit and function the same.

 

[Chiptosser]

The quality of steel does not affect the degree of flex (bowing). Quality does affect the ultimate yield point. -----and elongation.

It certainly does Your telling me that D2 tool steel or an other high strength allowed steel, has the same properties of a mild steel?

Most of the copy tool holders are made of lower grade steels, and some are not heat treated like higher quality brands.
They don't flex the same.
The design is not proper for the application to prevent unwanted elongation.

 

[rklopp]

The quality of steel does not affect the degree of flex (bowing). Quality does affect the ultimate yield point. -----and elongation.

It certainly does Your telling me that D2 tool steel or an other high strength allowed steel, has the same properties of a mild steel?

Most of the copy tool holders are made of lower grade steels, and some are not heat treated like higher quality brands.
They don't flex the same.
The design is not proper for the application to prevent unwanted elongation.

Dazz is correct. The elastic modulus is what counts and it is the same for mild steel and D2 in the tool holder context. The value is about 30 million psi or 207 GPa.

 

[Chiptosser]

Ah, so it is, I should have look at the chart before yapping.
The shear Modulus, or modulus of rigidity is different.
Just so others are not confused by this, Your mild steel component is not the same material quality as high chrome steel.

 

[Steamchick]

Possibly not the right place to post this, but it is something I have done a few times, and have made 3 bars - as well as used some my Father made. I hold the bars in a 3 jaw chuck, with a pop-mark at jaw no.1 for re-setting.

I have also made boring bars for vertical application in the Mill-drill, with the tool set on the end - both perpendicular to the axis, and at 30 or 45degrees to the axis as suits the bottom of the bore I am machining. This bar I mount in collets in the quill. I admit to enjoying boring cylinders this way, hand feeding the cut, and listening to the cut to ensure the feed is really smooth and evenly applied.
Usually, I measure the tool-point to the opposite side of the bar, when on a known cut/bore size, it is easy to use the micrometer - set at say 0.010" more than whatever dimension you have to add the cut - in this case by 0.010" - or whatever you want. In the video, she uses a square tool bit in a broached hole, but usually I use round bits in round holes.
Enjoy "Boring". I do.
K2

 

[Mike Ginn]

I think Quinn makes her bar with the square hole correctly but who has a broach? For light cuts I always use a round cutters with a ground flat if necessary. So much simpler to make. I would also question filing a square hole in thick(ish) material. Its really difficult - possible - but difficult.

 

[stanstocker]

I think Quinn makes her bar with the square hole correctly but who has a broach? For light cuts I always use a round cutters with a ground flat if necessary. So much simpler to make. I would also question filing a square hole in thick(ish) material. Its really difficult - possible - but difficult.

If you do want to put a square hole in something fairly thick there are a few tricks that help if you don't have a broach or a press that is large enough to press the broach through.

1) Drill slightly oversize. No reason to have perfect contact in the middle third of the flats.
2) Rough out the corners with a saw if possible. Just making a cut into the corner helps establish the square and the corners neatly for final work.
3) Use a square file, in good shape, a bit smaller than the hole at the tip. Refine each corner a few strokes at a time. As the file goes deeper, it will tend to align itself and maintain the hole shape.

Gathering pallets for tall clocks break or get damaged fairly often, and have a quite small tapered square hole that is around 4+ times as deep as it's pilot hole. I used to make a lot of these from 1095 ground stock. Once I figured out establishing the corners using a jewelers saw and using a square file to work the opening into proper form my life got a lot easier. At least as easy as it can be when making a long tapered square hole that's often around 1/16 inch on a side in steel.

For a larger square hole, it's worth considering poking a small hole just inside each corner before drilling out most of the waste. Putting a flat on round stock where the square is to be created always helps too. I've used this approach to poke 1/4 inch square holes now and then. I don't do enough of them to justify buying or making a broach.

For boring bars, you could drill to just make a sliding fit on the cutter, and use the clamping screws to hold things in place. If picky, just a few quick passes with a file would make a locating flat if you feel it's needed.

Cheers,
Stan

 

[Mike Ginn]

Hi Stan
I agree with all you say and in an ideal world the hole would be square. I just find making a squarish hole in say 1inch bar very time consuming and not really necessary if you can use round HSS with a flat. Fortunately I made a set of boring bars many many years ago and these work fine. I guess if you really need a square hole then a broach might be justified or use of hand tools as you describe. I always find such hand tool work is speeded up by a nice glass of wine!
Mike

 

[wazrus]

Like many, i have a collection of boring bars, for both chuck work and between centres. The between centres type shown in other contributors' has the cutter bar hole directly across the diameter. Most bars I've made have had their tool holes at an angle across the bar axis, largely to allow an outside micrometer to take a reading. Very much more convenient to adjust the cut than when the tool is projecting - even a small amount - on the other side. i don't see a need, either, to cut a square hole, but round as Mike Ginn suggests. The hole angle doesn't really matter, but a possible 'benefit' might be that the bar could be stiffer., especially with a smaller bar. If boring from the saddle, I very much prefer to lock the cross-slide in one position for the entire process and not use the lathe screws to adjust the cut.