开云体育

ctrl + shift + ? for shortcuts
© 2025 Groups.io
  1. Unimat
  2. Topics

First attempts - finish on brass (all?)

William Ayerst
 

开云体育

Hello there chaps,

After the kind advice to try out a cannon and the location of the Edenstaal plans on the files part of this group, I thought I’d test out the lathe again after a period of hibernation.

I am using a Unimat SL. The tool that came with the lathe was 1/4” HSS, so I have replaced this with a 6mm set from RDGTools (and after some experimentation, a 0.31mm shim underneath the tool, to return it to the height of a 1/4” tool). Now, using a left-handed cutting/facing tool I can cut across the diameter of a rod and get no ‘pip’. If I use a parting off fool, I get chips and very small curls of brass appearing, instead of chatter/etc.

I wanted to experiment with getting a good surface finish, so I am using a straight turning tool, as I understand it:

(Type-3 ST Turning)

This is the result:
The leftmost section has been polished with some emery paper while in the lathe, the right hand side is au naturel

If this is as good as I can expect, then that’s fine - but I’m going with as fine a cut as I can (the smallest subdivision on the cross slide) and as slow as seems reasonable (1-2mm per second longitudinally.

If anyone could give me some guidance as to what I’m doing wrong - or what I need to do differently, I would greatly appreciate it.

Many thanks,
 

For brass a round nose bit will give a smooth surface, with a pointed tool it's like you are cutting a thread.

Sent from my Huawei tablet


-------- Original Message --------
Subject: [Unimat] First attempts - finish on brass (all?)
From: William Ayerst
To: [email protected]
CC:


Hello there chaps,

After the kind advice to try out a cannon and the location of the Edenstaal plans on the files part of this group, I thought I’d test out the lathe again after a period of hibernation.

I am using a Unimat SL. The tool that came with the lathe was 1/4” HSS, so I have replaced this with a 6mm set from RDGTools (and after some experimentation, a 0.31mm shim underneath the tool, to return it to the height of a 1/4” tool). Now, using a left-handed cutting/facing tool I can cut across the diameter of a rod and get no ‘pip’. If I use a parting off fool, I get chips and very small curls of brass appearing, instead of chatter/etc.

I wanted to experiment with getting a good surface finish, so I am using a straight turning tool, as I understand it:

(Type-3 ST Turning)

This is the result:
The leftmost section has been polished with some emery paper while in the lathe, the right hand side is au naturel

If this is as good as I can expect, then that’s fine - but I’m going with as fine a cut as I can (the smallest subdivision on the cross slide) and as slow as seems reasonable (1-2mm per second longitudinally.

If anyone could give me some guidance as to what I’m doing wrong - or what I need to do differently, I would greatly appreciate it.

Many thanks,

IMG_20200419_111234_resized_20200419_111358649.JPG

 

This is one of my test pieces straight from the lathe, it was mostly cut with a standard straight cut tool as shown in the second picture.

Sent from my Huawei tablet


-------- Original Message --------
Subject: [Unimat] First attempts - finish on brass (all?)
From: William Ayerst
To: [email protected]
CC:


Hello there chaps,

After the kind advice to try out a cannon and the location of the Edenstaal plans on the files part of this group, I thought I’d test out the lathe again after a period of hibernation.

I am using a Unimat SL. The tool that came with the lathe was 1/4” HSS, so I have replaced this with a 6mm set from RDGTools (and after some experimentation, a 0.31mm shim underneath the tool, to return it to the height of a 1/4” tool). Now, using a left-handed cutting/facing tool I can cut across the diameter of a rod and get no ‘pip’. If I use a parting off fool, I get chips and very small curls of brass appearing, instead of chatter/etc.

I wanted to experiment with getting a good surface finish, so I am using a straight turning tool, as I understand it:

(Type-3 ST Turning)

This is the result:
The leftmost section has been polished with some emery paper while in the lathe, the right hand side is au naturel

If this is as good as I can expect, then that’s fine - but I’m going with as fine a cut as I can (the smallest subdivision on the cross slide) and as slow as seems reasonable (1-2mm per second longitudinally.

If anyone could give me some guidance as to what I’m doing wrong - or what I need to do differently, I would greatly appreciate it.

Many thanks,

IMG_20200419_111747_resized_20200419_111955933.JPG
IMG_20200419_111913_resized_20200419_111956793.JPG

 

Also for a finishing cut ramp up the speed and take a fine, very slow cut. Try to be as smooth as possible with the hand wheels. A dab of oil might help too.?
 

开云体育

Strictly speaking brass needs no, or a slight negative rake on the tool. This removes the tendency for the tool to dig in.

?

I guess that most of these general purpose packs are ground with rake angles for steel so that probably isn’t helping.

?

In practice I mostly use the same tools on brass and steel though, but most are ones I’ve ground myself and don’t (for example) have that ‘trough’ that you see on the off the shelf tool.

?

If you can grind your own tools from blanks then grinding a simple knife tool is straightforward enough – it’s parting, boring and thread cutting ones that are difficult.

?

Regards, Andy

?

From: [email protected] [mailto:[email protected]] On Behalf Of William Ayerst
Sent: 19 April 2020 09:43
To: [email protected]
Subject: [Unimat] First attempts - finish on brass (all?)

?

Hello there chaps,

?

After the kind advice to try out a cannon and the location of the Edenstaal plans on the files part of this group, I thought I’d test out the lathe again after a period of hibernation.

?

I am using a Unimat SL. The tool that came with the lathe was 1/4” HSS, so I have replaced this with a 6mm set from RDGTools (and after some experimentation, a 0.31mm shim underneath the tool, to return it to the height of a 1/4” tool). Now, using a left-handed cutting/facing tool I can cut across the diameter of a rod and get no ‘pip’. If I use a parting off fool, I get chips and very small curls of brass appearing, instead of chatter/etc.

?

I wanted to experiment with getting a good surface finish, so I am using a straight turning tool, as I understand it:

?

(Type-3 ST Turning)

?

This is the result:

The leftmost section has been polished with some emery paper while in the lathe, the right hand side is au naturel

?

If this is as good as I can expect, then that’s fine - but I’m going with as fine a cut as I can (the smallest subdivision on the cross slide) and as slow as seems reasonable (1-2mm per second longitudinally.

?

If anyone could give me some guidance as to what I’m doing wrong - or what I need to do differently, I would greatly appreciate it.

?

Many thanks,

?
 

开云体育

It also occurred to me that you said you were using a left handed tool.

?

If you are turning with the tool moving towards the headstock (which is the more usual situation) then you should use a right handed tool. LH is for cutting away from the headstock, usually up to a shoulder.

?

Regards, Andy

?

From: [email protected] [mailto:[email protected]] On Behalf Of Andy Carlson
Sent: 19 April 2020 11:52
To: [email protected]; willayerst@...
Subject: Re: [Unimat] First attempts - finish on brass (all?)

?

Strictly speaking brass needs no, or a slight negative rake on the tool. This removes the tendency for the tool to dig in.

?

I guess that most of these general purpose packs are ground with rake angles for steel so that probably isn’t helping.

?

In practice I mostly use the same tools on brass and steel though, but most are ones I’ve ground myself and don’t (for example) have that ‘trough’ that you see on the off the shelf tool.

?

If you can grind your own tools from blanks then grinding a simple knife tool is straightforward enough – it’s parting, boring and thread cutting ones that are difficult.

?

Regards, Andy

?

From: [email protected] [mailto:[email protected]] On Behalf Of William Ayerst
Sent: 19 April 2020 09:43
To: [email protected]
Subject: [Unimat] First attempts - finish on brass (all?)

?

Hello there chaps,

?

After the kind advice to try out a cannon and the location of the Edenstaal plans on the files part of this group, I thought I’d test out the lathe again after a period of hibernation.

?

I am using a Unimat SL. The tool that came with the lathe was 1/4” HSS, so I have replaced this with a 6mm set from RDGTools (and after some experimentation, a 0.31mm shim underneath the tool, to return it to the height of a 1/4” tool). Now, using a left-handed cutting/facing tool I can cut across the diameter of a rod and get no ‘pip’. If I use a parting off fool, I get chips and very small curls of brass appearing, instead of chatter/etc.

?

I wanted to experiment with getting a good surface finish, so I am using a straight turning tool, as I understand it:

?

(Type-3 ST Turning)

?

This is the result:

The leftmost section has been polished with some emery paper while in the lathe, the right hand side is au naturel

?

If this is as good as I can expect, then that’s fine - but I’m going with as fine a cut as I can (the smallest subdivision on the cross slide) and as slow as seems reasonable (1-2mm per second longitudinally.

?

If anyone could give me some guidance as to what I’m doing wrong - or what I need to do differently, I would greatly appreciate it.

?

Many thanks,

?
 

This is where the power feed option really shines

Martin P.

-----Original Message-----


Also for a finishing cut ramp up the speed and take a fine, very slow cut. Try to be as smooth as possible with the hand wheels. A dab of oil might help too.?

William Ayerst
 

Ok I have ordered a "traditional" 1/4" tool to try rather than the very pointy straight cut tool I have. I am planning on making the edenstaal cannon so a mix of aluminium and steel - so hopefully I'll have all the tools I need to get it done.

I will also try a higher speed - was using 1400rpm and trying to go as slowly and lightly as possible.

Thank you!
 

Hi William,
On the subject of cutting tools, have you considered learning to grind your own tools? Adding this skill to your “tool box” will enable you to grind any shape you will ever need not to mention the cost savings.
Also consider using smaller tools such as 3/16” square. They require less metal removal and are therefore quicker to grind and regrind.
Dick
 

开云体育

Hi Gang:

I used my Erector set motor for power feed once. The transmission allowed 2 speeds, forward and reverse. Plus since it drove the hex nut holding the hand wheel on it could drive all three hand wheels, carriage, cross feed and the tailstock! But since I don't mind turning the knobs I never use it.

Carl.

On 4/19/2020 8:50 AM, Martin P. via groups.io wrote:

This is where the power feed option really shines

Martin P.

-----Original Message-----


Also for a finishing cut ramp up the speed and take a fine, very slow cut. Try to be as smooth as possible with the hand wheels. A dab of oil might help too.?

 

Do you have any pictures of how you set that powerfeed up looking to add a power feed to my sl.

Dan
 

The simplest power feed is simply to use an electric screwdriver fitted
with a socket that fits the hex nut at the end of the screw. This gives
you both forward and reverse, and in many models variable speed.
You can thank Uncle Mert for this tip.


On 4/19/20 1:03 PM, Daniel via groups.io wrote:
Do you have any pictures of how you set that powerfeed up looking to add
a power feed to my sl.

Dan
_._,_._,_
------------------------------------------------------------------------
--
Elliot Nesterman
elliot@...
www.ajoure.net

"The finest jewel cannot disguise a flawed character."
 

Another option might be a sheering tool; I've used them on steel with great results, but never tried brass.? Has anyone?

-Dave

On Sunday, April 19, 2020, 01:43:40 AM PDT, William Ayerst <willayerst@...> wrote:


Hello there chaps,

After the kind advice to try out a cannon and the location of the Edenstaal plans on the files part of this group, I thought I’d test out the lathe again after a period of hibernation.

I am using a Unimat SL. The tool that came with the lathe was 1/4” HSS, so I have replaced this with a 6mm set from RDGTools (and after some experimentation, a 0.31mm shim underneath the tool, to return it to the height of a 1/4” tool). Now, using a left-handed cutting/facing tool I can cut across the diameter of a rod and get no ‘pip’. If I use a parting off fool, I get chips and very small curls of brass appearing, instead of chatter/etc.

I wanted to experiment with getting a good surface finish, so I am using a straight turning tool, as I understand it:

(Type-3 ST Turning)

This is the result:
The leftmost section has been polished with some emery paper while in the lathe, the right hand side is au naturel

If this is as good as I can expect, then that’s fine - but I’m going with as fine a cut as I can (the smallest subdivision on the cross slide) and as slow as seems reasonable (1-2mm per second longitudinally.

If anyone could give me some guidance as to what I’m doing wrong - or what I need to do differently, I would greatly appreciate it.

Many thanks,
 

I use a mini screw gun as my drive unit to return the carriage to the tailstock end ...On my U3. Works great.? I put a nutdriver on my screwgun and away it goes.? I will often use the screwgun to do roughing cuts in both directions
 


Generally those tool sets have? some top rake on them for turning steel. or maybe aluminium. For brass you need zerotop rake - a plain flat top to the tool. With top rake the tool tends to dig in, and then you can only take the lightest cuts - very light even by Unimat standat?ds. Then grind it to have a sharp point, and take the very tip of it off. Then you need a steady feed on the handwheel to get an even surface. This can be done by practiceing, or you could rig up some sort of drive, like an electri screwdriver. The other thing to do is make sure the slideways are snug. No slack at all, but moving smoothly. That will help to reduce vibration.

1 - 15 of 15