[m_caces]

Hello !

I'm new in the forum and also in the machining world. I'm from Chile and last month I acquired a CNC machine (A tormach 770) which has been a pleasure to work with.
I have some knowledge about machining from watching a lot of youtube videos and some free courses on the web but the area is far from my formal experience field (electrical engineer).

Lately I had been machining some parts, fiddling with the speed and feed parameters and everything has been going pretty well ... until the second OP came. What's happening is the two sides of the pieces are shifted [Figure 1]. I'm not using a vise stop because I do not have one yet (hope it arrives in the next weeks with a pair of 1-2-3 blocks).

Here are some questions. Please feel free to add all the information you want.

1 - I'm buying 1 meter long square stock (using delrin because ease of use ) and using a saw to cut smaller pieces for machining. When I do this, it is necessary to face mill the cut ends? Or is necessary to square the whole stock?. I'm using the raw stock as a base and the first operation is a face mill [Figure 2] (coordinate system used for the first setup/job is the back left corner of the raw stock) then using the machined surface as reference for the second operation [Figure 3]( because the lack of a vise stop I'm measuring G54 again and using a parallel to probe the face of the part hidden by the remaining stock and then adding the parallel width).

2- What other methods for selecting a 2nd op reference frame do you recommend?. I been tempted to use a pilot hole trough the stock and then use it's center to locate the X and Y vectors but this would required a machined face for the 2nd op in order to set the Z coordinate, but that is only applicable when the piece has a hole that goes through it. If this could not be possible (for example the piece does not have a hole) what options do you have?.

3 - This a more specific question about SolidCAM but I noticed the CAM programs work in a similar way. For what I'm defining the Coordinate System [Figure 4] ? I'm asking this because each setup let me define a new origin [Figure 5] and to me it seems redundant. Also, I do not understand what the offset tab means in each setup configuration window [Figure 6] and I set it to Work Coordinate 54 because when I probe the reference faces with the Haimer, the G54 option is used.

Any advice will be of great help.

Thank you for your time in advance.

[servtech]

Hello !

I'm new in the forum and also in the machining world. I'm from Chile and last month I acquired a CNC machine (A tormach 770) which has been a pleasure to work with.
I have some knowledge about machining from watching a lot of youtube videos and some free courses on the web but the area is far from my formal experience field (electrical engineer).

Lately I had been machining some parts, fiddling with the speed and feed parameters and everything has been going pretty well ... until the second OP came. What's happening is the two sides of the pieces are shifted [Figure 1]. I'm not using a vise stop because I do not have one yet (hope it arrives in the next weeks with a pair of 1-2-3 blocks).

Here are some questions. Please feel free to add all the information you want.

1 - I'm buying 1 meter long square stock (using delrin because ease of use ) and using a saw to cut smaller pieces for machining. When I do this, it is necessary to face mill the cut ends? Or is necessary to square the whole stock?. I'm using the raw stock as a base and the first operation is a face mill [Figure 2] (coordinate system used for the first setup/job is the back left corner of the raw stock) then using the machined surface as reference for the second operation [Figure 3]( because the lack of a vise stop I'm measuring G54 again and using a parallel to probe the face of the part hidden by the remaining stock and then adding the parallel width).

2- What other methods for selecting a 2nd op reference frame do you recommend?. I been tempted to use a pilot hole trough the stock and then use it's center to locate the X and Y vectors but this would required a machined face for the 2nd op in order to set the Z coordinate, but that is only applicable when the piece has a hole that goes through it. If this could not be possible (for example the piece does not have a hole) what options do you have?.

3 - This a more specific question about SolidCAM but I noticed the CAM programs work in a similar way. For what I'm defining the Coordinate System [Figure 4] ? I'm asking this because each setup let me define a new origin [Figure 5] and to me it seems redundant. Also, I do not understand what the offset tab means in each setup configuration window [Figure 6] and I set it to Work Coordinate 54 because when I probe the reference faces with the Haimer, the G54 option is used.

Any advice will be of great help.

Thank you for your time in advance.

If the material is soft and jaw marks aren't a problem, use serrated jaws to hold the material.
Also, do your roughing cuts toward the fixed vise jaw for maximum rigidity. Many people machine soft vise jaws to retain the material to stop it moving, ie. has a shoulder to butt against.

[6061billet]

It's one of the things that no one tells you, but fixturing can be one of the most complicated problems to solve.

Using a drilled hole to probe for the x-y on op 2 is a very common technique. But, as you mentioned, the Z coordinate it a bit more difficult. How you solve this depends on your clamping system. If you have a fixture plate then when you flip the part, the op1 top side becomes the z0 at the bottom and you can reference off of an accessible area of the fixture plate. If you are using soft jaws in a vice then you can mill a z reference feature into the soft jaws to probe off of. If you are using a vise with standard jaws then you might be able to reference off of the top of your parallels, that really depends on how much clearance you have. It also depends on what type of volume you are producing. If is this low production then there are a lot of things that you can do with a DTI to pickup a reference.

Usually I make a fixture that the part will nest in and I have the z height of the part controlled by whatever reference features that I've milled into the fixture. An that that point since the fixture is constraining the part you can pickup a z height of any reference area that you machine into the fixture. I often make small fixtures that I can just clamp in my vise.

You could also make mill a round plug with a shoulder on the end. When you insert the plug from the bottom into your reference hole, it will stop on the shoulder and you can probe the top of it an get a known distance from the opposite face.

I don't use this often, it depends on the side finish that you need and the thickness of your part. If you have enough thickness then you can profile the part all the way around to 1/2 the part depth. Then lay two 1/8" or 3mm parallels flat on the vice jaws. put the part in so the remaining shoulder sits on the parallels. Clamp the part in the vice then remove the parallels. Now if you probe off of the top of the vice jaws then center point of your part is the vice jaw height plus the thickness of the parallels that you used. This is a variant of TopHat machining. Usually it's done with soft jaws and flip. This video kinda shows the technique, but since the part has a built in step, he doesn't need the parallels to raise the part a known distance.

https://www.youtube.com/watch?v=I3VQ7fIWUYY

This one shows measuring a z height off of the parallels.
https://www.youtube.com/watch?v=TyW3zZ52gLs

These might also give you some ideas.
https://www.youtube.com/watch?v=9yfxGwHxp-E
https://www.youtube.com/watch?v=iM8OcPt8Pr4
https://www.youtube.com/watch?v=Liujqlj2cb0

[m_caces]

Hi !

Thank you for your feedback.

I've been machining and trying new methods and this is what is giving me the best results. In pictures <Stock Example> and <Stock Example 2> I´ve be trying to square stocks only using 2 Operations. The facing operations are done toward the fixed jaw in order to avoid sliding of the material. You can see where both operations collide.
What is bothering me the most is this phenomenon happening in the back of the part, which is always put with the fixed jaw and using a vise stop (thousand time more prone to move than the fix jaw) I got better results in the left face.

For the piece shown I started with a previous square stock ( I started with a piece of 100mm x 85mm previously machined and started removing 5mm per side each time, so the stock for this operation was the part from the previous). Because I started with a stock of known dimensions the piece was set in the center of the stock and 2.5mm were removed from each side. The WCS for the first operations (G55) was set using a 1-2-3 block and offsetting 2.5mm into the block for X and Y axis (see <Fixture OP1>) and for Z the top of the parallels was used. At the same time I set the second operation WCS (G56) using the same block but without substracting the 2.5mm and using the same Z as G55. <Top View>


I have some questions regarding the second operation, for what I've seen in practice it should be used mainly for facing operations and removing of the leftover stock remaining from previous operations. But avoid doing contours in "halves" and buy larger mills ?.

Hope to get better results soon and share them with you.

Best regards.