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View Full Version : Tips for working on material longer than my x axis travel?



wdfwguy
06-29-2019, 01:47 PM
I knew I might run in to this issue when I bought my mini mill. But let's say the x-axis travel is 12", and I need to mill slots in a piece that is 16" long...

Short of buying a larger mill (although I'm thinking about it), how do I go about moving my work piece and maintaining as much accuracy as I can?

754
06-29-2019, 02:05 PM
Circular edge stops that fit in your t slots.. i.e. a stepped bushing, smaller diameter fits t slot. Both have to be identical diameter..

LKeithR
06-29-2019, 03:23 PM
A set of 5C collet blocks and a few collets is the ideal answer. You can easily index in 90 degree
and 60 degree increments...

https://www.banggood.com/Machifit-5C-Collet-Block-Chuck-Set-Square-Hex-Collecy-Closer-Holder-Lathe-Tools-Kit-p-1377416.html?gmcCountry=CA&currency=CAD&createTmp=1&utm_source=googleshopping&utm_medium=cpc_union&utm_content=2zou&utm_campaign=ssc-ca-all-july&ad_id=353631916062&gclid=EAIaIQobChMI7OPs97SP4wIVGMNkCh3z8Qs7EAQYAiAB EgIKLvD_BwE&cur_warehouse=CN

Magicniner
06-29-2019, 03:24 PM
Planning and fixturing.

Bented
06-29-2019, 04:14 PM
A lot of vices
https://photos.smugmug.com/photos/i-G5Xzxg2/0/042ffe47/L/i-G5Xzxg2-L.jpg (https://bented.smugmug.com/General/n-zRzxZF/i-G5Xzxg2/A)

110" part in a 60" machine.

strokersix
06-29-2019, 04:49 PM
I've done some inline six chevrolet block deck surfacing on machines way way way too small. One tip is to use a hanging weight from a pulley on the ceiling to support the overhung workpiece.

epicfail48
06-29-2019, 06:36 PM
Depends on the accuracy you need. Non-super critical you could probably get away with keys in the t slots. Butt your workpiece against the keys, clamp it as appropriate, mill the first section, unclamp, slide the piece down while maintaining contact with the keys, re-clamp, resume machining. If more accuracy is needed, use the keys for initial alignment and follow up by aligning the previous cut with the direction of travel with a DTI

darryl
06-29-2019, 07:20 PM
I built a matching pair of vises to mount on my mill table. Requires some alignment as they do not key into a T-slot, but that's fairly quickly done. Loosen both, slide workpiece, tighten, repeat.

Basically what you need is a fence aligned in the X direction. This is your reference edge as you move the workpiece along and re-clamp for each segment of the machining.

Doozer
06-29-2019, 07:51 PM
Do you even indicate, Bro??

-Doozer

Paul Alciatore
06-29-2019, 09:25 PM
Yes, that's why I purchased two milling vises. Line them up carefully and do the slot one section at a time




A lot of vices
https://photos.smugmug.com/photos/i-G5Xzxg2/0/042ffe47/L/i-G5Xzxg2-L.jpg (https://bented.smugmug.com/General/n-zRzxZF/i-G5Xzxg2/A)

110" part in a 60" machine.

rjm13365
06-30-2019, 08:54 AM
When faced with this on a Lucas HBM w/ 5" spindle and 8' table,I would set the part up centered on table.Do center area,then move part to do one end, indicating on part of center area, then repeat on opp. end.Could do machine frames over 16 feet long w/ no problems.That was about 30 yrs. ago.Retired now.

LKeithR
06-30-2019, 12:29 PM
Depends on the accuracy you need. Non-super critical you could probably get away with keys in the t slots. Butt your workpiece against the keys, clamp it as appropriate, mill the first section, unclamp, slide the piece down while maintaining contact with the keys, re-clamp, resume machining. If more accuracy is needed, use the keys for initial alignment and follow up by aligning the previous cut with the direction of travel with a DTI

This would work fine for square or rectangular stock but I have one suggestion. Take the time to indicate the
keys to ensure that they're in perfect alignment. Just bolting them to the table will get you close but probably
not perfect. If you're working on a piece of round material you need to align it horizontally to the table but also
radially so that the keys will line up. Using keys gives you no positive way of doing that.

As I mentioned in my previous post a simple collet block set will handle a setup like this just fine with virtually
perfect alignment. If your stock is larger than the largest 5C collet size I've gone so far as to machine a short,
smaller diameter step on one end of a shaft to use with a collet. It's easy to cut it off and clean up the end of
the shaft afterwards...

MrWhoopee
06-30-2019, 05:21 PM
A set of 5C collet blocks and a few collets is the ideal answer. You can easily index in 90 degree
and 60 degree increments...



Dammit, I thought I had just acquired the last thing I "really needed". I have a square one I made in school, but I never finished the hex. See what you've done?!

Rich Carlstedt
06-30-2019, 08:19 PM
I use dowels a lot. Sometimes I make holes in a part and use them for set up.
Say you want a slot 16 inches long with only a 10 inch table travel. Have your edge stops set or use a vise
Then center the part (!) on the X axis , and then drill two holes at a even number apart , like 8 inches ( less than travel limit, BUT Accurately !) so 8.000 .
Now put a dowel to match hole size in the quill and release the work piece. Center the table and insert the dowel(w/Quill) into the part in one of the holes and clamp. Reset your DRO of indicators or dials and mill your slot. Since we need 16" total, we can do 4" and 3" on either side of this hole, or 7 inches !.....but do not mill into the other hole. Record how far you went outward ( like 4.000 ) . Now release the part, and redo the dowel setting with the quill and the work piece centered in travel . Clamp and set your dials/DRO)

Now if you machined say 4.000 outward on the other hole, and the holes are 8 " apart, ( 12.000") you now know how much further to machines outward on this hole --and you can move to continue the slot and know exactly where to stop.--- A 16 inch slot with 10 inch travel, but you only used 8 inches ~ of it .
Whats neat is this can be used with 1/4" dowel pins, while the slot mill can be bigger...just remember to account for diameter of cutter in the calculations

Rich