# Newbie Here



## leegscott (Mar 2, 2021)

I am so glad I found you guys this morning. I have been watching you tube videos for the past 6 months trying to decide on which mill to purchase. The general advice that I have been given is buy as large as I can afford. I have also been told that regardless if I purchase a new one (import) or a used one there will be things that I will need to adjust or correct. However, at least with a new mill, parts will be easier to find. As of last week I was down to two, the Grizzly G0755 & G0731. However; it was recently suggested that I consider the PM-940V mill. Wow, it does look good to me and there are quite a few videos of them being converted to CNC capabilities which is what I would want to do - so there are footsteps I can follow and hopefully some of you will be willing to coach me along the way.

My primary hobby is experimental rocketry. I am needing to machine aluminum parts as well as I would like to be able to machine composite parts from composite plates that I make.

If anyone has any advice on the mill PM-940V or might have another suggestion, please share it with me. I know that it has been done before but I will post pictures and a video of the build. I will continue going through the you tube videos as well as this forum (a lot of info to sort through) for upgrades that I should consider when I have the mill apart.

I plan to call Precision Mathews this month and get it ordered.

Thanks again and I am excited I found you! There is a huge amount of knowledge on your forum which I recognize the value as well as the time that has been put into it.

Lee


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## Cadillac STS (Mar 2, 2021)

One idea if you are definitely going to go CNC is to see if there is one with a full CNC conversion kit available.  Then buy the kit, install it and you are done.  Otherwise you will need to source parts and figure out how to get it altogether.  

Maybe search CNC conversion kit for mill and see what comes up.  There may be one for the PM machine you want too.

Would be nice to know before you bought something that would be a major project to convert to CNC.


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## brino (Mar 2, 2021)

Hi Lee,

Honest, I am NOT trying to make your machine decision any more difficult.
But I have a few thoughts.

I dunno about "as large as you can afford"......I do subscribe to "as large as you need for your largest part or project"

Much of rocketry stuff is cylindrical (nose cones, engine nozzles, etc.) have you thought about a lathe?

Welcome to the group!

-brino


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## ttabbal (Mar 2, 2021)

Welcome! Always nice to see another rocketry nut around here. I know some of the PM mills have CNC conversion kits available, and some others that have done it. I have a PM lathe and I've been very happy with it.


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## BladesIIB (Mar 2, 2021)

Welcome Lee. I don’t have a PM mill but like others above, I have a PM Lathe and have been very happy with it. I have a Jet mill drill and if I had found PM before buying it, I would have preferred a PM mill. Will likely upgrade to one at some point. Like Brino, I am curious if you need a lathe for all the round parts on your rockets?  What projects are lined up for the mill?  Space is also a consideration when picking the machine. Largest you can afford is OK, but consider the space, what other equipment you will need to add etc. Space gets used up fast.


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## leegscott (Mar 2, 2021)

Guys thank you so much for the responses! I do have access to a lathe and have used it a few times. I am planning on purchasing one at some point but my current bigger need is a mill.

I am wanting to machine rocket fins out of both aluminum and composites. I believe the maximum dimensions of the fins will be 9” in the y axis and 18” in the x axis (mill terms). I am hoping that I can machine them in a circular arc airfoil or a double wedge from the leading edge to trailing edge with an option to taper from root to tip (all rocket terms). I believe that both of these shapes will be difficult to machine which is why I am planning on spending the money for CNC which appears to be as expensive as the lathe.

Now if you guys think I can possibly do it with a smaller mill that would be great!!! I was planning to look at the y travels tonight of the smaller mills.

Again I am so glad I found you guys!

lee


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## leegscott (Mar 2, 2021)

I mentioned lathe when describing price of cnc for lathe I meant to say mill but I think the dollars would apply to both. You never can have enough room in the shop. If you guys think it would be close with a smaller mill, I would be willing to take that chance to be able to invest more in the cnc


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## BladesIIB (Mar 2, 2021)

Sounds like you have done some research and have a plan. 9x18” is a good size piece. You should be able to find the best PM mill for the job, and likely one of the larger ones. Sounds like a lot of fun. I only used CNC during my apprenticeship many years ago so don’t know much about that other than videos I see. Very cool indeed. Enjoy!


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## Larry$ (Mar 3, 2021)

Even if the largest part you now have need for will fit a smaller mill that doesn't mean you won't want to make a larger part next year! I mostly do repair work so I've pushed the limits of the part sizes my machines can handle. My 9x49 Jet knee mill only has an X travel of just over 30", i don't remember exactly what it is. Y travel can be increased by sliding the ram out and ending up with quite a lot. Z travel is the most likely to be run out of, for me. Especially for boring


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## brino (Mar 3, 2021)

leegscott said:


> I plan to call Precision Mathews this month and get it ordered.


.......oh one more thing, and I am still not trying to be a downer.....

From what I have read here, you should set your expectations that there will likely be some delays, just like everything else these days.
Not sure if it's the unloading delays and container ship backups in California or what.

Please let us know where it leads.
Good Luck!

-brino


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## leegscott (Mar 3, 2021)

Guys I was looking at the PH-833VT ultra precision mill last night. Does anyone have an opinion regarding if the added dollars for what is advertised as better quality machine would be worth sacrificing the size of the larger table size of the PH-940v. The PH-833VT Y travel is 11" which I believe will be plenty for a 9" wide piece of material. I noticed a you tube video that showed an aluminum plate that was milled flat and then clamped to the table and then the part clamped to the plate for machining. I believe that machining something 9" in the y axis would be the exception and not the rule. In addition, it would give me a little more space in the shop. However, I will be paying more for a smaller machine for what is advertised as better quality because it is fabricated in Taiwan. Any opinions would be appreciated and as I said in an earlier post I will be converting the mill that I decide on to CNC.  

Thanks

Lee


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## BladesIIB (Mar 3, 2021)

I am assuming you mean PM machines in your post above?  If so, or even brand aside, personally, I would pay extra for 100% Taiwanese model. In the size you are looking for if you are going to put it on a stand and not a bench you may want to consider the knee mills to get a little larger and stay 100% Taiwan. Jump in price and no idea the impact on turning to CNC. When I upgrade it will be to a knee mill. Not much larger footprint for the PM-935TV and a truly versatile machine that will be good quality.


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## Cadillac STS (Mar 3, 2021)

Maybe contact PM and ask the question which mills can be easily converted to CNC or have a full kit.  And ask if they could put on ball screws as stock so you would not need to do it for CNC conversion later.


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## leegscott (Mar 3, 2021)

Thanks and yes PM jssh


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## Cadillac STS (Mar 4, 2021)

CNC will be nice for working on rocket fin parts and other things.


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## leegscott (Mar 4, 2021)

Good information! 

I am probably at the Mill B option. PM-833TV. I am planning on building my own tube steel base because I am going to build a custom acrylic enclosure with a sloped bottom covered with a EPDM sheet to make cleanup of chips easier. The tube steel base will be topped with a 1/2" thick plate and topped with the EPDM and then the mill will be will sit on top of the plate & on top of the EPDM. I am also going to build custom cabinets on each side of the base with drawers. Currently planning on using the Acorn board with ClearPath Servo motors and Heavy Metal double ball nuts and premium ball screws. Currently trying to decide on the servo size for the z drive screw, how many separate power supplies / amplifiers for the drives and misc. equipment. Currently the plan is 1 for the x & y motors, 1 for the z drive motor and 1 for the acorn board and other misc. stuff. I am also planning on a cooling fog mister, a couple of cameras with a raspberry pi so that I can record the milling process for when things do not go as plan. The touch screen monitor will be on a separate tube steel post with some attachments for misc. tools, air hose, & small shelf mounted all mounted to the floor to the right of the enclosure. My shop also has a grounded dust vac system and I plan to have a port on the tool holder stand. The electronics enclosure will be mounted on the shop wall behind and to the left of the mill enclosure. Once I figure out the electronics (mainly power supplies) I will be able to size the electronics box and draw it up in cad for everyone to review, if you interested.

Again if anyone has an opinion on my current plan or any other upgrades that I should consider please let me know.

Thanks

Lee


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## leegscott (Mar 4, 2021)

Blades. I noticed you call home in Texas. I was born in Dallas and raised in Katy Texas. I am a graduate from Texas A&M University (please don't hold that against me if you color is Orange with horns). Work brought me to California about 30 years ago. I love the California weather but miss the Texas people. The majority of the people here all seem to be in a hurry!


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## BladesIIB (Mar 4, 2021)

Lee, I have been fortunate to live quite a few places and yes Texas has been home for the last 11 years, in addition to 6 years some time ago.  I live in North East Dallas and do enjoy Texas.  No offense on A&M, I went to school in Arizona but my son will attend A&M so I guess I am connected to an Aggie now. I look forward to pics of your build. May inspire me to tackle CNC myself.


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## 7milesup (Mar 4, 2021)

Welcome aboard @leegscott.  Have a seat.  Buckle up and prepare for the ride!!  All of us on here will gladly help you spend your money, and even possibly give you some advice.  
I have an PM-833T mill.  The TV version came out after I bought mine, which is a real bummer.  I too would like to convert mine to CNC, but the straight "T" version is harder to do because of the geared head vs the belt drive.  I will do it eventually but too much to do right now.  Most likely a next winter project.
As far as Taiwan vs Chinese, I feel that the difference is significant.  I had a PM-1022 lathe (Chinese) that I just sold and bought at Eisen 1440E lathe (Taiwan), and I will say the difference between the two is night and day.  Of course, the 1440E cost nearly 4x what I paid for the 1022 initially but the 1440 is a thing of beauty.

Below is a link to a guy that has done a CNC conversion to the PM-833TV.  He did a real nice job but learned a few things along the way.  He went sort of cheap to start with utilizing stepper motors vs servo and using a single ball nut vs a double, so he ended up redoing some of it.  He has it all documented , which he did a fantastic job on including a BOM.

---->PM-833TV Converted<---
--->Upgraded PM-833TV<---
And his website....--->Dr. D. FLo website <---

Side note.... I would love to see your projects with the rocketry down the road.  When I was a kid my brothers left some Estes rockets laying around.  I started to mess with them which then piqued my interest in RC aircraft which then kindled a spark in full size flying.  30 years and 9000 hrs of flying later, I had to retire due to a medical issue.


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## leegscott (Mar 4, 2021)

7 miles up. I would be glad to share my rocket stuff. If your interested, you can look at my website www.scottrocketry.com. Been into rockets since 2007.

I launched a rocket in September that went to 31,500 ft (just a little short of 6 miles up) that I still need to add to the website. 

The reason for the mill is to be able to machine materials that I can use in the construction of the rockets. The rocket in September was traveling at Mach 1.5 which creates heat and strength of material issues. 

Sorry to here about you having to give up flying but when one door closes another opens which I have learned with my own getting older health challenges.


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## 7milesup (Mar 4, 2021)

Well... you could have almost reached me with your 6 mile rocket while I was cruising at 7 miles up!
That is some pretty serious rocketry!


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## 7milesup (Mar 4, 2021)

One other thought Lee regarding the CNC conversion.  No matter which mill you choose, I would highly suggest a system to counterbalance the head of the mill.  The 833's head is very heavy and believe that either a counterweight or an air cylinder would greatly help movements in the Z axis.  D-Flo has not done that and it will most likely develop issues later on.  You will most likely have air at the mill for mist cooling anyway, so a counterbalance air cylinder would be the a good choice.


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## Cadillac STS (Mar 4, 2021)

I think it is a great thing you are building a full cabinet for the mill. Would be so nice to close the door and keep everything inside. You could do flood coolant if needed.


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## leegscott (Mar 5, 2021)

Ok counter balance, will do. I will start researching tomorrow. If you guys can direct me to those that have already done it that would be great. I have stumbled across at least one example already. I think I would prefer counterweight and depend on gravity instead of cylinders and a mechanical operation. One less thing that could go wrong.

Again thanks for the advice!!

Lee


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## leegscott (Mar 6, 2021)

I am having a hard time finding any info on how to control the spindle speed of a mill drill that is already a variable drive. Could anyone direct me to a website, YouTube, or thread on this forum, or a vendor contact for information? I will be using acorn for control.

thanks
Lee


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## ttabbal (Mar 6, 2021)

leegscott said:


> I am having a hard time finding any info on how to control the spindle speed of a mill drill that is already a variable drive. Could anyone direct me to a website, YouTube, or thread on this forum, or a vendor contact for information? I will be using acorn for control.
> 
> thanks
> Lee




Depends on the speed controller. Most of the CNC controllers seem to have a few options for output. And VFDs at least usually have a few as well. You match them up and configure both ends to use the same signal. 0-10V analog signals seem to be pretty common, as one example.


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## ArmyDoc (Mar 6, 2021)

Hi Lee,  welcome aboard.  I was going to suggest you look at a 3D printer as an alternative or adjunct,  but reading further it looks like you are doing a much larger / faster rocket than I was picturing.
So, one other consideration for you.  For the price you will pay for a PM40 or 833TV, you would be close to the price of a used Tormach, which would already be CNC ready, and likely be more capable.

Sorry to open the Rabbit hole further, and welcome to the club.


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## leegscott (Mar 6, 2021)

Thanks for the suggestion and yes I am already using a 3d printer. I have had it for a couple of years and have done a few modifications to it which gave me the confidence to attempt CNC. I have pretty much made up my mind on the mill and I am pretty deep into determining all of the components plus I am learning something new which is good!

thanks again

lee


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## 7milesup (Mar 6, 2021)

I agree Lee.  You are heading down an interesting path and learning is part of the experience.  
I know a lot of guys like the Tormach, and it is a very nice system but, if you are willing to put the time into developing your own CNC with available components, you will end up with mill that is just as good, or better.  
One of the issues I have considered with my 833T is the Z axis "nod".  There is a slight nod that I can see with my DRO when I tighten down the locks on the gibs.  The thought goes through my mind about utilizing 25mm linear rails on the Z axis.  I have not fully considered the route of implementation  though.


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## Ischgl99 (Mar 6, 2021)

If you are going to CNC the mill, you might want something that gives you more repeatable tool offsets than an R8 would.  You might want to call PM and ask if they can supply a spindle with something like a BT30 taper.  That will enable you to program your tool lengths into the CNC controller and not have to touch off each time you change your tool.  PM also has a CNC page on their website, there is no content, but maybe they have something planned that you can look into as well.


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## leegscott (Mar 10, 2021)

Today I sent a e-mail to Precision Matthew’s new purchase technical support and I asked the status of the new manual specifically the electronics of the PM-833TV. The response confirmed the machine was the same as the 833t  except for the VFD instead of gear head. Below is part of their response.

“It does run on a VFD, but its not exactly the same as the typical programmable VFDs, this manual will not have info on how to change settings. It is a VFD, but without the case and the keyboard for parameters. Worst case you could just replace with a common VFD that you are familiar with, the motor is just an inverter motor, so can run fine from that too.”

The way I read it is that the VFD that comes with the machine will not take commands from the controller which in my case will be a Acorn. It looks like I will need to purchase a new VFD for the CNC conversion.

Do you guys interpret it the same way. Regardless, I am still planning on purchasing the PM-833TV next week but will just need to include a VFD with the rest of the CNC parts.

thanks for any advice

lee


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## Ischgl99 (Mar 10, 2021)

Sounds to me like they have it programmed to do what they want it to do and you can’t change it unless you can find a way to get a keypad or programming cable for it.  Many VFDs are able to be programmed from a laptop with the correct communications cable, the trick will be finding the right software for it if they don’t tell you which unit the guts came from.


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## ArmyDoc (Mar 11, 2021)

If you can find out what board it is, it may very well be the same as others that are out there.  In which case you can get a manual from them that will tell you how to program it.


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## leegscott (Mar 11, 2021)

Guys thanks for the advice. I am at the 9th hour ready to pull the trigger. What are your guys thoughts on the tightening of the spindle to the drawbar? A couple of weeks ago I had pretty much decided on the PM-940 but after reading that the quality of the PM-833 was a little better as it was manufactured in Taiwan. So I was going to go with the smaller mill for about $1,000 more.

Do you guys know if the quick change or easy change tool holder (depending on which country I purchase it from) will solve the being able tighten spindle problem.

Also do you guys think it is better to go with the smaller Taiwan machine (more expensive) or the larger less expensive PM machine manufacturer in China.

I plan to call precision Precision Mathews today and discuss it with them.

thanks for any advice 

lee


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## Cadillac STS (Mar 11, 2021)

Maybe consider going with the Tormach system for quick replaceable collets.  Will want to set up tool lengths in advance for tool changes for a CNC program anyway so need to have a quick change system.



			https://littlemachineshop.com/images/gallery/Instructions/DS10052_TTS_Catalog.pdf


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## leegscott (Mar 11, 2021)

Thank you for sharing


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## 7milesup (Mar 11, 2021)

Did you see the thread on H-M here that someone did a drawbar lock system on their 833TV?  I am on my phone so searching and pasting is not easy to do otherwise I would link it.
As Cadillac mentioned,  the Tormach system may be a good choice or even an ER style collet adapter.


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## leegscott (Mar 11, 2021)

Thanks and yes I did. I was just second guessing my mill choice and I am going to stick with it. I exchanged a e mail with Bruce at Heavy Metal CNC today, I spoke with Tom at Teknic and he has since e mailed me a list of parts including servo model numbers with an invoice. I spoke with John at Precision Mathews around lunch to talk about spindle lock issue and talked about PM-833 vrs 940 differences. I am selecting misc. parts from cnc4pc website now. I was looking at Ruland split jaw spider couplings earlier. Just need to figure out how long they should be. I have my Centroid list complete. 

My bank account is going to take a hit on Monday. 

Thanks all,  for your advise.

It will soon be all about making what I have work instead of what should I purchase.


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## BladesIIB (Mar 11, 2021)

So did you decide on the 833?  I would go with the Taiwan machine if everything else works. I don’t know the CNC conversion side but I do think the Taiwan quality is worth the little extra for it.   Just my 2 cents, sounds like you are there and in for a lot more than 2 cents. Good luck, I look forward to tracking the build.


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## leegscott (Mar 11, 2021)

Thanks and yes I did. I was just second guessing my mill choice and I am going to stick with it. I exchanged a e mail with Bruce at Heavy Metal CNC today, I spoke with Tom at Teknic and he has since e mailed me a list of parts including servo model numbers with an invoice. I spoke with John at Precision Mathews around lunch to talk about spindle lock issue and talked about PM-833 vrs 940 differences. I am selecting misc. parts from cnc4pc website now. I was looking at Ruland split jaw spider couplings earlier. Just need to figure out how long they should be. I have my Centroid list complete.

My bank account is going to take a hit on Monday.

Thanks all,  for your advise.
It will soon be all about making what I have work instead of what should I purchase.


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## leegscott (Mar 11, 2021)

Cadillac or 7mile I think one or both of you guys might have the 833. If so, could one of you verify what the bottom of the Machine base would be if I wanted my table height to be 34 1/2”

thanks

lee


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## leegscott (Mar 11, 2021)

It does not need to be exact. Thanks!!!


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## leegscott (Mar 11, 2021)

After I read my post did not sound so good. Let me re ask the question. If you do not mind could you measure? Sorry


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## 7milesup (Mar 11, 2021)

Yep, I can do it tomorrow.  Just came in and it is getting late here.


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## 7milesup (Mar 12, 2021)

The distance from the mill table to the bottom of the mill base is 10-1/8".  My stand is 36-1/2" tall giving a height from floor to mill table of 46-3/4".


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## leegscott (Mar 12, 2021)

Thank you very much!


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## 7milesup (Mar 12, 2021)

I would like to see your CNC build once you get all the parts together.  I am seriously considering doing a CNC conversion to mine.


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## leegscott (Mar 13, 2021)

You got it! I did wake up at 2am worried about the 10k I was about to spend and not even sure that the CNC machine could produce what I want. So I have put a pause on that. I am going to use fusion 360 and draw up what I am wanting to machine and then send the file to a real machinist to machine. If that works I will purchase the machine and CNC stuff. I explained it to my wife at dinner tonight and I think she was a little relieved. I hope you guys do not feel like I have run you through the popcorn machine because you all have been so helpful!!! Starting tomorrow afternoon I will be watching YouTube videos to teach me how to use fusion 360. If you are interested i will share the progress of the 3D model I design and then what the real machine shop produces from it.


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## Ischgl99 (Mar 13, 2021)

If you haven’t already found videos on Fusion360 you like, I watched the 16 part series Arnold Rowntree produced and it was extremely helpful.  I was completely lost before watching that and decently proficient afterwards.  Lars Christensen is also an excellent teacher.  I would be interested in the progress of your model, I am curious how you design and build it.


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## brino (Mar 13, 2021)

leegscott said:


> If you are interested i will share the progress of the 3D model I design and then what the real machine shop produces from it.



Yes please!
-brino


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## leegscott (Mar 13, 2021)

I will definitely share and thanks for suggesting the 16 series. I will start that this morning!


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## leegscott (Mar 13, 2021)

Lschgl99 thank you for suggesting the videos. I just watched part 1 in my shop while eating breakfast. This is going to be very helpful! I am going to watch it again in the morning and draw the part as he explains the steps. But for now going to have to shut down the shop. I promised my wife today would be her day. Going to take her to the beach and have lunch at a outdoor restaurant and then walk along the boardwalk. Now I would have to admit I would prefer to be working in my shop today but happy wife happy life.

thanks again 

lee


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## 7milesup (Mar 13, 2021)

^^^  I dunno man.  If I could go to an outdoor restaurant and go for a walk on the boardwalk, I would be all over that.  Freaking year of isolation along with a winter thrown in for good measure, I'm ready to go do something.  Have fun!


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## Ischgl99 (Mar 13, 2021)

I’m with 7milesup, your shop will be there when you get back, enjoy a nice day with your wife.  And yes after the winter we have had, I am jealous you can sit outside for lunch, it is 41 here today, but at least all the snow is gone. 

I drew what he did in the videos as well and that helped a lot with understanding and retaining the knowledge.  I don’t recall now how much he covered with doing drawings, but the drawing section has everything you need to dimension your prints and you can use GD&T symbols as well if you like that.  I use them extensively being a former engineer.


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## leegscott (Mar 13, 2021)

It was a nice day. Temperature was in the low 60’s. Sun felt nice. She had a hamburger and I had a salad with chicken. We walked for awhile and then sat at another outdoor restaurant and had a couple of glasses of wine as the sun went down over the ocean before driving home. I should be in the clear for a couple of weeks. I will be in the shop tomorrow. 7mile glad things are warming up in your neck of the woods. Hopefully you will be able to do the same soon!

lee


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## leegscott (Mar 13, 2021)

Lsgchgl99 just saw your post hope you will be able to do the same soon. Got to admit I like going up in the mountains here and visiting the snow for a couple of days but that’s it. I do like the weather here but really miss the people in Texas. The main problem with Texas is it gets damn hot in the summer not to mention the humidity. But hey breathing, losing a little weight feeling good, can’t complain to much.


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## Ischgl99 (Mar 14, 2021)

leegscott said:


> Lsgchgl99 just saw your post hope you will be able to do the same soon. Got to admit I like going up in the mountains here and visiting the snow for a couple of days but that’s it. I do like the weather here but really miss the people in Texas. The main problem with Texas is it gets damn hot in the summer not to mention the humidity. But hey breathing, losing a little weight feeling good, can’t complain to much.


We tolerate the winters here for fantastic spring, summer and especially fall weather   I live at 1,000 ft elevation at the top of a hill, so the summers are not that bad and we get a nice breeze.  Now the 50 mph winds in the winter, that's another story!  I retired from engineering and am now doing photography full time so I can raise the kids while my wife travels, I spend as much time as I can in the "mountains" around here, there is some incredible scenery nestled into this small state.


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## 7milesup (May 12, 2021)

Any progress to report on the CNC conversion?


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