Author Topic: Fitting DROs to a small milling machine  (Read 7032 times)

Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 15294
  • Hampshire, england.
Fitting DROs to a small milling machine
« on: October 08, 2012, 09:16:22 AM »
Last year for my long service award I had the opportunity of spending ?750 on myself. The idea of a gold watch didn?t hit the mark so I decided to treat myself to a set of DRO?s for two of my milling machines. This is how I fitted up one of them my Prazimat mill:

The Prazimat is similar to many of the bench top mills you can purchase, it has a substantial cast Iron Table and a round column.  Following advice from the suppliers I purchased the mounting plates for all the scales, some of which were purchased much longer than the scales they were for, this was to enable mounting the scales on the machine.

I started with the scale for the X axis. I had decided to mount it at the back of the table, which would reduce the movement by about ?? but was less likely to be knocked or get in the way during use. The first step was to mount the scale cover, first the back plate was clamped in place and the mounting holes drilled and tapped.

With the backing plate in position it was now possible to look to measure up for the head mounting. On the Prazimat the most desirable place to mount the head is immediately in front of the column but with the column in the way it would be impossible. So my answer to this was to make a slightly wider head mounting and to drill and tap on either side of the column using a ratchet tap wrench:



The final job in mounting the scale is to bolt on the glass scale and then using a dial gauge check that there is no run out. Once the scale is level then the head, once appropriately shimmed can be bolted down to its mounting.

 

The vertical scale mounting presented a number of challenges as the column base is tapered, whilst the head is much narrower. I purchased an over length mounting for the vertical and for the bottom made a wedge that compensated for the taper on the cast iron base. Having measured the resulting off set of this face from the column I then measured the distance from the column to the head which gave me the required depth of the offset piece for the top of the column mount. I then need to check that I had mounted the backing plate vertically:

 

To enable access to the clamps at the back of the mill head it would be necessary to offset the scale head so that it sat below the clamps. This was achieved using a Z shaped piece of aluminium, which enabled the head to sit here:



Before going any further I wound the mill to its maximum and minimum height and from this worked out where to mount the scale on the backing plate based on the highest and lowest mounting point for the head.




This is the vertical scale in place, hopefully I should not need to put my hand around the back by the head now that it is in place. The red plastic objects either side of the head provide for the correct spacing of the head from the sacle, once the head is bolted down these are removed :D.

 

The final scale for the Y axis I decided to fit behind the right hand, it could have been fitted to the left hand side but that would have meant that the cable would have got in the way.



This took a bit of jiggery pokery as I had to offset the scale away from the mill bed to enable the head mounting to pass behind the scale mount:




Finally after two days I had this:


The DRO has transformed this mill, it has gone from being a very expensive drill to being an impressive piece of kit that is very accurate (I had not realised before how accurate it was) that I use for 95% of my co-ordinate drilling and milling  :whoohoo:.

I also fitted a similar set up to my Harrison Milling machine :pinkelephant:... but that is another story.

Jo
Enjoyment is more important than achievement.

Bogstandard

  • Guest
Re: Fitting DROs to a small milling machine
« Reply #1 on: October 08, 2012, 10:24:48 AM »
Jo,

I used to be a bit of an old school machinist, doing everything by hand and counting wheel rotations.

I did fit an old type Chinese scale system onto my old RF mill, and suffered for ages trying to keep it constant, and alive. It cost me an absolute fortune to keep going.

I purchased my new lathe and mill about 4 years ago, already fitted with a good quality DRO system, and by adding a few extra glass scales and read heads, it has transformed the way I work, not only is it super accurate, but I can concentrate a lot more on producing better and better surface finishes, saving many hours on clean up times.

The only other major additions that could be added to make it even better is power feeds, and I am lucky on that score as well, all mill axis and two lathe axis were fitted when I bought the machines.

If anyone was looking to upgrade their machines, fitting a good DRO must be a priority as far as I am concerned.

Just enjoy.

John

Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 15294
  • Hampshire, england.
Re: Fitting DROs to a small milling machine
« Reply #2 on: October 08, 2012, 11:43:59 AM »
Hi John,

Whilst I am very happy with my DRO's on the mills ;D, I have yet to be convinced if putting them on the lathe is a good investment.

As you will have seen I use dial gauges on most of my lathes to measure the X and Y movement. I tried mounting a set of cheapo magnetic gauges on my Prazimat lathe but was not impressed found it harder work to read the digital read out than to use the dial gauges. So I still need convincing as to investing in DRO's for the lathe.

Jo
Enjoyment is more important than achievement.

Bogstandard

  • Guest
Re: Fitting DROs to a small milling machine
« Reply #3 on: October 08, 2012, 01:46:07 PM »
Jo,

My situation at that time was a little different. I was setting up a fairly high precision jobbing shop, where 0.001" was no use as a tolerance, I was working to 0.0002", and the DRO's gave me that every time, and even though I had to give up that enterprise due to ill health, I have found that very close tolerance has become the norm if needed, without even thinking about it. But normally I now use the old system of 0.002" if it isn't too critical.

It is just the ease of use that works for me.

Measure, zero up, put the cut on, spot on size.

John

chuck foster

  • Guest
Re: Fitting DROs to a small milling machine
« Reply #4 on: October 08, 2012, 01:54:40 PM »
jo,

i used dial gauges on my 9" south bend lathe for years then i put a dro on the lathe and what a difference!
the lathe is far more accurate and easier to use. now having run the lathe with a dro i would never have another lathe without a dro installed.

were do you work?? long service awards.................gee's must be nice........i have been at the same job for 20 years and all i get is the boss yelling at me to get back to work.  :Lol:

any who nice write up and thanks for showing how it was done.

chuck


Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 15294
  • Hampshire, england.
Re: Fitting DROs to a small milling machine
« Reply #5 on: October 08, 2012, 02:23:50 PM »
jo,

were do you work?? long service awards.................gee's must be nice........i have been at the same job for 20 years and all i get is the boss yelling at me to get back to work.  :Lol:

I am not admitting to how many years service it was for ::).

Jo
Enjoyment is more important than achievement.

Offline Don1966

  • Full Member
  • *****
  • Posts: 6817
  • Columbia, MS
Re: Fitting DROs to a small milling machine
« Reply #6 on: March 07, 2013, 06:23:37 PM »
Jo, you will find that DRO's on a lathe is a great asset. For one cutting stock to size, I first move my tool to the work by just touching it and by knowing what size the stock is,subtracting the size I want it to from it. I then enter the amount I want to remove in the DRO and as I cut before I reach .010 I check the work with a micrometer it's usually spot on. Then I zero the scale and finish to size from that micrometer reading. Just a sample of the time it saves. It also remembers your zero position and you can program multi length points. There are plenty other uses as you will find.

Don


 

SimplePortal 2.3.5 © 2008-2012, SimplePortal