BT40 Haas retension knobs for odd ball CAT40 holders

viper · Mar 8, 2008

I have a CAT40 spindle on our Haas and have some odd ball tooling that has the CAT40 V flange, but accepts metric BT40 retention knobs. I can get BT40 knobs but the knobs are all .110" longer from seat to first first taper on the knob. CAT40 is .989 and the BT40 is like 1.02". I am curious if this will cause retention problems or not?? Can I get the right length knobs for my application?

We also have a couple BT40 holders that we would like to just use for measuring tools that will not cycle in the TC. Are the CAT40 and BT40 spindles the same minus the difference in spindle height for tool change?

fmari --MariTool- · Mar 8, 2008

The BT40 and CAT40 spindles are the same on the HAAS machines. Just the tool changer fingers are different. If you can't match the pull stud head height do not use the tool in the spindle. The height form the gage line to the pull stud head must remain the same.

viper · Mar 8, 2008

I have yet to find a stud that has the same length as my CT40 studs. Is there a place I can go to get something like this? Guess I should call and ask Haas about this so do not jack something but I have some really nice holders with a bunch of collets. Probably worth it to find some knobs.

gregormarwick · Mar 9, 2008

My hurco has a cat 40 spindle and all of my cat 40 tooling has a metric M16 pull stud thread.

I'm in the UK, my toolholders are DIN69871/SK40/DV40/CAT40, all the same form factor, all have metric pull stud thread, tbh the only toolholders I've seen with an imperial thread are 40 ISO ones.

Perhaps that may give you some leads?

Also when you're comparing pull stud length between cat40 and BT40 you need to bear in mind that the gauge length is different. You have to measure from the gauge diameter on the taper rather than the flange, as they are not the same between CAT and BT. From memory, the pull stud needs to be longer on a BT40 to reach the same length from the gauge line on the taper to the collar on the pull stud.

I good way to check is to put each toolholder in a bench fixture or a 40-50 sleeve (so that the toolholder is sitting on the taper, not the flange) and measure how far the top of the pull stud is sticking out.

I hope my poor explanations make some kind of sense!

Gregor

viper · Mar 9, 2008

That is kinda what I was wondering. I need to find a site that has some dims of holders so I can figure out what I have and need. I do notice the BT40 is shorter from the top of the BT flange to the end of the taper but the difference is like .150

Chazsani · Mar 9, 2008

Pull Studs/Retention Knobs

Looking at the Rutland Tool & Supply catalog, 2008r53, Pg 739, there may be some information that helps you. You may also go online to www.rutlandtool.com and get the info if you do not have the catalog. Hope this helps.
Chazsani

SchneiderMachine · Mar 9, 2008

http://catalogs.shoplocal.com/jlind...loggedin=false&newbanner=true&storeid=1038424
Pages 1084-1087
HTH's
Dave

Walt @ SGS Inc. · Mar 10, 2008

BT 40 tool holders..

If you were to measure the difference between BT and Cat holders, you would find they are much the same except for the 40s. For some reason they made one tool holder longer than the other. The metric BT holders are about .113" shorter than the inch Cat holders. The best way to measure this is with a female taper gage and a height gage. After all, the tool seats on the taper therefore you need to set the tool on a taper and measure the end of the tool holder. Then determine where the retention knob has to be located and then you will know which kob will give you the proper tool retention.
Don't know why they made them different lengths. Seems like the 40 taper is the only one that has this difference.
Regards Walt..

viper · Mar 10, 2008

I do not have a taper set to test the gauge height with. I think I will have to make a call to Haas and see if they can offer the right dims for this application and confirm the draw bar will work fine for this. I would about bet the knobs I am finding that are .100 longer will comp the shortness of the BT40 holder and will work correctly but I guess I need to KNOW before I cost myself some coin by damaging something.

Uguessedit · Nov 22, 2019

Sounds like BT40 which are m16. Cat 40 have 5/8-11 threads. I have many of them and every time I order a cat 40 they are correctly threaded. I did order a BT40 once and it did not work it had m16 metric threads.

TeachMePlease · Nov 22, 2019

Uguessedit said:
Sounds like BT40 which are m16. Cat 40 have 5/8-11 threads. I have many of them and every time I order a cat 40 they are correctly threaded. I did order a BT40 once and it did not work it had m16 metric threads.

Pssst... He had the problem 11 years ago... Hopefully he's sorted it out.

Uguessedit · Apr 24, 2020

For anyone still wondering amazon has a lot of retention knobs for application specific tool holders. Frankly they’ve been the best price and easiest to find for us. Of course read reviews I’ve heard some claim they’ve received the incorrect ones. Even if one were to retap for the other the cat 40 knob is shorter and even if a spacer was used the taper on the head is slightly different which would add to an already risky use. The cat 40 knobs are $20 for qty 10 and the bt40 knobs are $45 for qty of 5. Personally if one were not well invested in bt40 I’d switch it all to cat 40 just to save some money besides it seems that tooling options are more plentiful in cat 40.

Uguessedit · Apr 24, 2020

It’s ok folks will continually be asking similar questions for years. Keeping old posts updated is good for anyone searching.

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