What are you machining?

[Kram]

I can turn hard steel with no problems, the inserts I use are unavailable now or I would recommend them. I'll admit its not easy to find a good insert for boring and hard steel complicates that a bit more.
Suggest a light finishing or stainless grade of carbide insert for boring. If it is really hard then the CBN inserts come out - but generally most items with a thread can be turned with carbide.

 

[fizzy]

I can turn hard steel with no problems, the inserts I use are unavailable now or I would recommend them. I'll admit its not easy to find a good insert for boring and hard steel complicates that a bit more.
Suggest a light finishing or stainless grade of carbide insert for boring. If it is really hard then the CBN inserts come out - but generally most items with a thread can be turned with carbide.

I don't have CBN but the inserts I am using are designed for hardened steels.
Shame those inserts you use are no longer available.
Here is a question for people.
I was lucky enough to win an auction for some solid carbide milling cutters. New and unused. Sadly not many and the biggest is 16mm. Very impressive quality and they are stupidly heavy. What is the difference between them and carbide tips? I can see that carbide tips are sintered but the solid carbide cutters don't seem to be.
What is the difference?
Really it was like a hot knife through butter. No wonder they are so expensive. A 20mm drill bit or end mill can be anything from £65 to £120.

 

[Kram]

There is a big difference. All carbide is sintered but endmills will be sintered as a round bar and then ground to shape, so the endmills are fully ground. Generally they have sharp but fragile edges and there are a vast choice of different grinds for different jobs. The edge hone chamfer/radius is rarely listed in the specs but very important.

The inserts after sintering, may be ground or just coated. Inserts that are as pressed will not have sharp edges but they will be extremely durable.
Some are designed for durability with deep roughing cuts. Big machine needed, not good for boring or hard steel. " Light finishing" are sharper, more like an endmill but with some durability.

You can get CBN inserts from a fiver, best to look for NOS on ebay but I have some chinese ones. CBN are less variable in that they are generally all ground the same way, but it doesnt particually like intermittent cuts or being knocked. That said I have turned a couple of large HSS drill flutes down with them and they didnt mind that.

 

[fizzy]

There is a big difference. All carbide is sintered but endmills will be sintered as a round bar and then ground to shape, so the endmills are fully ground. Generally they have sharp but fragile edges and there are a vast choice of different grinds for different jobs. The edge hone chamfer/radius is rarely listed in the specs but very important.

The inserts after sintering, may be ground or just coated. Inserts that are as pressed will not have sharp edges but they will be extremely durable.
Some are designed for durability with deep roughing cuts. Big machine needed, not good for boring or hard steel. " Light finishing" are sharper, more like an endmill but with some durability.

You can get CBN inserts from a fiver, best to look for NOS on ebay but I have some chinese ones. CBN are less variable in that they are generally all ground the same way, but it doesnt particually like intermittent cuts or being knocked. That said I have turned a couple of large HSS drill flutes down with them and they didnt mind that.

Forget CNC and the rest. The biggest advance in machining must have been the introduction of carbide tooling.
It amazes me to see huge depths of cut taken with small, cheap and fragile little tips. One little knock and they break but no problem with a 1/2" cut

 

[Kram]

Not just cutting tips, it has 3x the rigidity of steel so makes excellent tool bars. Next to QCTP and collet chucks, carbide boring bars are the best upgrade. Link below one similar to mine. I have 6 of them now. 2 smaller ones I dont use and will sell soon.

TS- C12M-SDUCR07 Solid carbide holder (Tungsten steel shock tool holder) DCMT21 | eBay

I'll send you a link.

www.ebay.com

Alternative is you can buy solid carbide bar blanks and grind them yourself or braze on a steel head with an insert pocket. I plan to do that soon and make a few extra ones.

 

[ukracer]

Forget CNC and the rest. The biggest advance in machining must have been the introduction of carbide tooling.
It amazes me to see huge depths of cut taken with small, cheap and fragile little tips. One little knock and they break but no problem with a 1/2" cut

Which reminds me....I must find out how to adjust the clutch on my Colchester master 2500 as it slows right down with large cuts.
My goto Guru for the 2500 was Ronan (RIP) but sadly he is no longer with us.

 

[ukracer]

Sounds easy but I tried finding a video on YouTube that covered it but sadly found nothing that helped.

 

[fizzy]

Which reminds me....I must find out how to adjust the clutch on my Colchester master 2500 as it slows right down with large cuts.
My goto Guru for the 2500 was Ronan (RIP) but sadly he is no longer with us.

Such a shame

 

[Kram]

Milled bar for radius tool

To get it on centre height theres only 3.5mm under the insert. I could have bored the radius tool with it raised up 5mm on a spacer, but this was much simpler to work out - I was intending to mill the 2.5mm deep insert recess with it on centre height and a 5mm endmill.
I might braze a section of 12mm ID tube underneath as support however that will reduce the maximum size ball that can be turned to about 29mm instead of 60mm. The insert pocket did not take long so I can always add another at other end with support. I will mill the insert shape later and stick weld in some walls to the insert pocket to stop rotation.

My lathe is again having problems with parting. I used up my last good chinese SP200 insert which confuses it a bit more. I think it is from having the big 8" chuck.
I'll have another go before I get the bandsaw/grinder out. It is raining at the moment so not wanting to work outside.

Ok parting "solved". I usually set the blade square against my collet chuck on the faced face of it with a parallel. Today I was trying to use the chuck face, between the jaws, which is an original surface. Appears it may be convex or at an angle. I also added a crude machinists jack under the parting holder, superglued for convinience, and it does appear to help.

 

[Kram]

Endmill could have been longer, not much left in collet chuck (I did have a spacer on the other end to keep collet in shape)

 

[minimutly]

Finished the gearbox flange for the SdKfz 251 Halftrack yesterday.

View attachment 439132 View attachment 439133 View attachment 439134

Nice, what material? How did you cut the splines?

 

[Kram]

I do like this protractor!

Insert pocket wedges just superglued in for now. I will braze them eventually. The left one is currently somewhere under the bench or in the bin and I spent a good while looking for it amongst the swarf before I made up a very quick replacement.

Smashed one of my few good boring inserts though being careless when test fitting a part

Edit: the intended purpose, works bloody brilliantly for it. Could use a longer handle to keep my fingers away from the swarf!

 

[Kram]

Somone did try to warn me the cutter would need more clearance but I didnt consider the bar itself would be a problem with this design . Milling the sides did not help much, the fix would be to weld a chunky bar support underneath and cut away the bar at centre height. That would limit the usable range of this bar, but no problem to make another insert pocket on the other end later.

View attachment 439541

 

[Onoff]

Somone did try to warn me the cutter would need more clearance but I didnt consider the bar itself would be a problem with this design . Milling the sides did not help much, the fix would be to weld a chunky bar support underneath and cut away the bar at centre height. That would limit the usable range of this bar, but no problem to make another insert pocket on the other end later.
View attachment 439536

View attachment 439541 View attachment 439544

Now it makes sense...sort of.

 

[Kram]

Set up this project for milling. First swapped belt and pulleys for higher speed 3k rpm. Clocked in the part, ready to cut I thought.

The fancy carbide endmills have a 4mm shank instead of 6mm on the chinese cutterss. It appears my er16 4mm collet is poo with 0.1mm+ runout, quite visible, I dont want to risk snapping them so easily.

The 6mm collet is acceptable but the cheap cutters are not. Tried my smaller er11 4mm, runout not slightly better. Er25 held in a questionable mt2 adaptor, not good.
Er32 doesnt have clearance with the nut.

Looks like I need to swap back to qctp and bore out a sleeve so I can use a er16 10mm collet

 

[Kram]

I got the collet to run true under 0.01mm , probably luck of several things cancelling out.

I'd say not bad for a plastic guided milling jig!

Lathe seems happy enough except the spindle did warm up to about 60c. First time I have noticed it leaking grease.

 

[ukracer]

I got the collet to run true under 0.01mm , probably luck of several things cancelling out.

View attachment 440476
I'd say not bad for a plastic guided milling jig!
View attachment 440477

Lathe seems happy enough except the spindle did warm up to about 60c. First time I have noticed it leaking grease.

I had one like that...lol

But I did mine on the mill

 

[Onoff]

I'd say not bad for a plastic guided milling jig!

My vision, my lad's design! Appreciate the hard work on this. Thanks to my lad, @ukracer, @Kram etc who tried, advised are trying!

I do wonder how much smoother the jig would have been if printed on say a Bambu or other top quality printer.

Looking pretty damn good though. Did you flip it 180 and do the other side or quit whilst you were ahead?

 

[Kram]

Flipped but not cut yet as I had to go out. I am planning to have a try with the stainless today.

 

[Onoff]

Flipped but not cut yet as I had to go out. I am planning to have a try with the stainless today.

I'm so excited and I just can't hide it!