Member postings for Y C Lui

The carbide insert in your picture looks like a molded insert which is blunt and is designed to be used on powerful machines taking deep cut. Switching to ground inserts will solve your the problem. I use carbide tools only on my hobby-grade lathe ( Emco Compact 8 ) to avoid grinding HSS tools. Have encountered the same trouble until I learned about ground inserts.

My lathe is an Emco Compact 8 which is just hobby grade so the power is low. For cutting steel, I could not use carbide parting tools of width more than 1.5 mm but even when the insert is so narrow, I could not part stainless steel until I switched to sharper inserts. The insert I am using now is ground instead of molded.  Yours seems to be molded. Will not work well on my lathe. Tool life of ground inserts is on the short side but given the low price, it's acceptable for me.

Edited By Y C Lui on 04/08/2022 05:26:17

That's backlash of the cross slide lead screw. My Emco Compact 8 bench lathe exhibits the same thing. The movement is about 0.1 mm, has never caused any problems. I would suggest to loosen the gibs completely and see if the limit of cross slide movement is still there. May be something is jamming the cross slide lead screw at the point where the cross slide cannot be moved further.

Yes, that sounds more logical for me because the amount of metal that need be removed will be far less hence saving in time and less wearing of tools and the machines. Furthermore, I just can't figure out any ways to cut out a nice joint between the ring and the rod. There will be steps of some kind there.

Looks like the kind of engine in my mind. Will need some time to study the drawing. E.g. What "BMS" refers to ( some kind of steel ? ). Some of the parts are also quite challenging to make with manual machines.  An example : 

How to fit the Teflon ring onto the piston is also puzzling unless the piston is split into two parts : 

Edited By Y C Lui on 21/07/2022 03:33:27

I think I will start with stationary steam engine and see how it goes.

I have been thinking about this for quite a while but not sure what addition tools that I will need. I have an Emco FB2 mill and a Compact 8 lathe so machining is no problem in general. Base on what I have read I may be lacking tools for cutting and forming sheet metal, silver soldering and may be steel hardening ? Currently I use carbide tools only as I don't have a grinder. Is there any frequent need for formed HSS tools ? What is the minimum requirement on tools and equipment to make my first steam engine ?

From your other posts it seems that your lathe is a Myford ML7. The tailstock locking mechanism is a bit different from that of my Emco Compact 8 which has got just one nut on the top that need be tightened to lock the tailstock. There is not any adjustment mechanism. On the Myford, it seems that you need to adjust the nut at the bottom :

Edited By Y C Lui on 15/07/2022 15:37:05

What is the drill size and the material of the workpiece ? If the material is not very hard and the diameter of the drill is not too large then the only explanation is that the drill bit is dull or the tailstock is not properly locked.

My Emco Compact 8 bench lathe is not too picky on oil. Almost any synthetic oil of medium viscosity works fine.

BUT when it comes to contact surfaces between zinc alloy and steel, Most of the greases I have tried did not work well. I could feel metal rubbing against each other after using it for a while. Finally I settled on a synthetic grease that came with my springer airgun upgrade kit. The seller has re-branded it so I do not know the original brand or type. It is designed to be used on the main spring of the airgun. It lubricates as well as dampens. The motion over those contact surfaces has been butterly smooth so far.

Thanks for all the answers. Just surprised by how much it takes to make a long straight hole.

My Emco Compact 8 lathe is equipped with a ER25 collet chuck which can hold workpieces of diameter up to 16 mm. The spindle has a MT3 taper bore so it should be possible to put in a MT3 ER32 milling arbor to hold larger workpieces. I am wondering if this is a good idea because if this works Emco would not have made a collet chuck. Inquiring mind will appreciate some answers .

I have been experiencing this for quite some time and usually it's not a problem because most of these holes are for accomodating bolts so the precision required is not very high.

However I am interested in knowing why. Is it because of the quality of the drill bits ? Just last week I drilled a 3.3 mm diameter, 33 mm long hole through a 7075 aluminium rod with my Emco Compact 8 lathe. A 3 mm spot drill was used to start the hole. I can put the drill through the resulting hole without any resistence but a 3.3 mm gauge pin would stop at about 3/4 of the length of the hole. If I insert the gauge pin from the other end, it stopped at 1/4 of the length indicating that there is a bend there. Wondering what the cause is and how it can be avoided.

Just can't understand why. I have tried this kind of tools ( 3 blades ) with positive or zero rake angle but once the cutting area gets larger ( > 6 mm ), it will chatter. May be it's due to the backlash of the feeding screw of the tail stock but how come no such problem has been encountered when drilling even if the diameter of the hole is much bigger ( 13 mm  ? The lathe is an Emco Compact 8.

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Edited By Y C Lui on 04/07/2022 15:47:36

My Compact 8 lathe can only do right hand.... Seems that I can shelve the plan for the time being

Making a new nut is now on my to-do list. Seems doable and I have two questions :

1) What kind of material will be the best ? It seems that SAE660 bronze is a more standard material for lead screw nuts but I can get 663 only. Will that be OK ?

2) The lead screw seems to have trapezoidal threads but I am not sure about the angle. There are two types : 30 and 29 degrees with 30 being more common. Does that one degree difference matter in practice ?

I noticed that the amount of movement of my edge finder upon contact has been reducing over time. Just wondering what the possible causes are. I have been using it to locate the corner of my vice only and that part of the vice has now become more shiny due to repeated rubbing by the finder. Can the increased smoothness of the surface be the reason ?

My machine is equipped with DRO so backlash is not a concern. As of now, the Z hand wheel can turn freely over 0.12 mm when the head is locked. The same amount is seen on the cross-slide hand wheel of my Emco Compact 8 lathe.

Even without DRO, the weight of the head should be sufficient to take out any backlash but that's assuming that the head can move very freely. For that to happen, the gib and bolts 39 will need be on the lose side which can hurt accuracy along the X axis.

Edited By Y C Lui on 30/06/2022 09:33:39

I would say thats likely to be the reason. The gibs as well as the other two bolts for Z axis play control are all on the tight side. When the head is lowered slowly, sometimes it would stop before suddenly fall by around 0.1mm before moving smoothly again. That zinc alloy nut always worries me so I have been exercising great care not to overload it. When I move the head upward, I always push the head upward with my hand at the same time in order to reduce the load on the Z nut.